Crime Scene Training

DNA 101 Part 1– A Basic Introduction to DNA Evidence

From National Institute of Justice Articles:

DNA Evidence Basics 

DNA collection and analysis gives the criminal justice field a powerful tool for convicting the guilty and exonerating the innocent. About Forensic DNA provides general information on a wide range of topics.

Only one-tenth of a single percent of DNA (about 3 million bases) differs from one person to the next. Scientists can use these variable regions to generate a DNA profile of an individual, using samples from blood, bone, hair, and other body tissues and products.

In criminal cases, this generally involves obtaining samples from crime-scene evidence and a suspect, extracting the DNA, and analyzing it for the presence of a set of specific DNA regions (markers).

If the sample profiles don't match, the person did not contribute the DNA at the crime scene.

If the patterns match, the suspect may have contributed the evidence sample.

DNA from crime scenes also can be compared to profiles stored in a database.

 Basics of Identifying, Gathering and Transporting DNA Evidence

Gathering DNA Evidence

Physical evidence is any tangible object that can connect an offender to a crime scene. Biological evidence, which contains DNA, is a type of physical evidence. However, biological evidence is not always visible to the naked eye. DNA testing has expanded the types of useful biological evidence. All biological evidence found at crime scenes can be subjected to DNA testing. Samples such as feces and vomit can be tested, but may not be routinely accepted by laboratories for testing.

Identifying DNA Evidence

Since only a few cells can be sufficient to obtain useful DNA information to help your case, the list below identifies some common items of evidence that you may need to collect, the possible location of the DNA on the evidence, and the biological source containing the cells. Remember that just because you cannot see a stain does not mean there are not enough cells for DNA typing. Further, DNA does more than just identify the source of the sample; it can place a known individual at a crime scene, in a home, or in a room where the suspect claimed not to have been. It can refute a claim of self-defense and put a weapon in the suspect's hand. It can change a story from an alibi to one of consent. The more officers know how to use DNA, the more powerful a tool it becomes

 

Evidence	Possible Location of DNA on the Evidence	Source of DNA
baseball bat or similar weapon	handle, end	sweat, skin, blood, tissue
hat, bandanna, or mask	inside	sweat, hair, dandruff
eyeglasses	nose or ear pieces, lens	sweat, skin
facial tissue, cotton swab	surface area	mucus, blood, sweat, semen, ear wax
dirty laundry	surface area	blood, sweat, semen
toothpick	tips	saliva
used cigarette	cigarette butt	saliva
stamp or envelope	licked area	saliva
tape or ligature	inside/outside surface	skin, sweat
bottle, can, or glass	sides, mouthpiece	saliva, sweat
used condom	inside/outside surface	semen, vaginal or rectal cells
blanket, pillow, sheet	surface area	sweat, hair, semen, urine, saliva
"through and through" bullet	outside surface	blood, tissue
bite mark	person's skin or clothing	saliva
fingernail, partial fingernail	scrapings	blood, sweat, tissue

Crime Scene Integrity

Protection of the crime scene is essential to the protection of evidence. Safeguarding and preserving evidence is fundamental to the successful solution of a crime. Remember, while documenting evidence at the crime scene, to include descriptions of whether evidence was found wet or dry. An example of this documentation would include blood spatters.

Contamination

The risk of contamination of any crime scene can be reduced by limiting incidental activity. It is important for all law enforcement personnel at the crime scene to make a conscious effort to refrain from smoking, eating, drinking, littering or any other actions which could compromise the crime scene. Because DNA evidence is more sensitive than other types of evidence, law enforcement personnel should be especially aware of their actions at the scene to prevent inadvertent contamination of evidence.

Chain of Custody

The chain of custody of evidence is a record of individuals who have had physical possession of the evidence. Documentation is critical to maintaining the integrity of the chain of custody. Maintaining the chain of custody is vital for any type of evidence. In addition, if laboratory analysis reveals that DNA evidence was contaminated, it may be necessary to identify persons who have handled that evidence.

In processing the evidence, the fewer people handling the evidence, the better. There is less chance of contamination and a shorter chain of custody for court admissibility hearings.

Transportation and Storage

The first responding officer may be called upon to transport evidence from a crime scene. As with any evidence, the officer should ensure that the chain of custody is maintained. In addition, they should be aware that direct sunlight and warmer conditions may degrade DNA, and avoid storing evidence in places that may get hot, such as the trunk of the police car. To best preserve DNA evidence, store in a cold environment.

Any probative biological sample that has been stored dry or frozen, regardless of age, may be considered for DNA analysis. Nuclear DNA from blood and semen stains more than 20 years old has been analyzed successfully using polymerase chain reaction (PCR). Samples that have been stored wet for an extended period of time should be considered for testing only using PCR and may be unsuitable for DNA analysis. Mitochondrial DNA analysis has been performed on very old bones, teeth, and hair samples.

Samples generally considered unsuitable for testing with current techniques include embalmed bodies (with the possible exception of bone or plucked hairs), pathology or fetal tissue samples that have been immersed in formaldehyde or formalin for more than a few hours (with the notable exception of pathology paraffin blocks and slides), and urine stains. Other samples such as feces, fecal stains, and vomit can potentially be tested, but are not routinely accepted by most laboratories for testing.

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DNA101 Part 2 – Basics of Analyzing DNA Evidence

DNA Evidence: Basics of Analyzing

Several basic steps are performed during DNA testing regardless of the type of test being done. The general procedpcr,strure includes: 1) the isolation of the DNA from an evidence sample containing DNA of unknown origin, and generally at a later time, the isolation of DNA from a sample (e.g., blood) from a known individual; 2) the processing of the DNA so that test results may be obtained; 3) the determination of the DNA test results (or types), from specific regions of the DNA; and 4) the comparison and interpretation of the test results from the unknown and known samples to determine whether the known individual is not the source of the DNA or is included as a possible source of the DNA.

Any probative biological sample that has been stored dry or frozen, regardless of age, may be considered for DNA analysis.

Each additional test at a previously untested locus (location or site) in the DNA provides another opportunity for the result of "exclusion" if the known individual being used for comparison is not the source of the DNA from an evidence sample of unknown origin. If, however, the known individual is the source of the DNA on the evidence sample, additional testing will continue only to include that individual as a possible source of the DNA. When a sufficient number of tests have been performed in which an individual cannot be excluded as the source of the DNA by any of the tests, a point is reached at which the tests have excluded virtually the world's population and the unique identification of that individual as the source of the DNA has been achieved.

Steps in DNA Sample Processing

Following is a review of the steps involved in processing forensic DNA samples with Short Tandem Repeat (STR) markers. STRs are a smaller version of the Variable Number Tandem Repeat (VNTR) sequences first described by Dr. Jeffreys. Samples obtained from crime scenes or paternity investigations are subjected to defined processes involving biology, technology, and genetics.

Biology

Following collection of biological material from a crime scene or paternity investigation, the DNA is first extracted from its biological source material and then measured to evaluate the quantity of DNA recovered. After isolating the DNA from its cells, specific regions are copied with a technique known as the polymerase chain reaction, or PCR. PCR produces millions of copies for each DNA segment of interest and thus permits very minute amounts of DNA to be examined. Multiple STR regions can be examined simultaneously to increase the informativeness of the DNA test.

Technology

The resulting PCR products are then separated and detected in order to characterize the STR region being examined. The separation methods used today include slab gel and capillary electrophoresis (CE). Fluorescence detection methods have greatly aided the sensitivity and ease of measuring PCR-amplified STR alleles. After detecting the STR alleles, the number of repeats in a DNA sequence is determined, a process known as sample genotyping.

The specific methods used for DNA typing are validated by individual laboratories to ensure that reliable results are obtained and before new technologies are implemented. DNA databases, such as the one described earlier in this chapter to match Montaret Davis to his crime scene, are valuable tools and will continue to play an important role in law enforcement efforts.

Genetics

The resulting DNA profile for a sample, which is a combination of individual STR genotypes, is compared to other samples. In the case of a forensic investigation, these other samples would include known reference samples such as the victim or suspects that are compared to the crime scene evidence. With paternity investigations, a child's genotype would be compared to his or her mother's and the alleged father(s) under investigation. If there is not a match between the questioned sample and the known sample, then the samples may be considered to have originated from different sources. The term used for failure to match between two DNA profiles is 'exclusion.'

If a match or 'inclusion' results, then a comparison of the DNA profile is made to a population database, which is a collection of DNA profiles obtained from unrelated individuals of a particular ethnic group. For example, due to genetic variation between the groups, African-Americans and Caucasians have different population databases for comparison purposes.

Finally a case report or paternity test result is generated. This report typically includes the random match probability for the match in question. This random match probability is the chance that a randomly selected individual from a population will have an identical STR profile or combination of genotypes at the DNA markers tested.

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DNA101 Part 3 – Types DNA Evidence Analysis

Polymerase Chain Reaction (PCR)

Short Tandem Repeats (STR)

Y-Chromosome

Mitochondrial DNA

DNA Typing — Polymerase Chain Reaction (PCR)

The evolution of DNA testing advanced significantly when Dr. Kary Mullis discovered that DNA could be copied in the laboratory much as it is in the natural world.

The copying process, known as polymerase chain reaction (PCR), uses an enzyme (polymerase) to replicate DNA regions in a test tube. By repeating the copying process, a small number of DNA molecules can be reliably increased up to billions within several hours.

Image of RFLP and PCR blood sizes

RFLP analysis requires a biological sample about the size of a quarter, but PCR can be used to reproduce millions of copies of the DNA contained in a few skin cells. Since PCR analysis requires only a minute quantity of DNA, it can enable the laboratory to analyze highly degraded evidence for DNA. On the other hand, because the sensitive PCR technique replicates any and all of the DNA contained in an evidence sample, greater attention to contamination issues is necessary when identifying, collecting, and preserving DNA evidence. These factors may be particularly important in the evaluation of unsolved cases in which evidence might have been improperly collected or stored.

DNA Typing — Short Tandem Repeat (STR) Analysis

Short tandem repeat (STR) technology is a forensic analysis that evaluates specific regions (loci) that are found on nuclear DNA. The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. For example, the likelihood that any two individuals (except identical twins) will have the same 13-loci DNA profile can be as high as 1 in 1 billion or greater.

The Federal Bureau of Investigation (FBI) has chosen 13 specific STR loci to serve as the standard for CODIS. The purpose of establishing a core set of STR loci is to ensure that all forensic laboratories can establish uniform DNA databases and, more importantly, share valuable forensic information. If the forensic or convicted offender CODIS index is to be used in the investigative stages of unsolved cases, DNA profiles must be generated by using STR technology and the specific 13 core STR loci selected by the FBI.

More details on STR Analysis:

Thirteen core STR loci used by the FBI (STRBase)

STR Data Analysis and Interpretation for Forensic Analysts (free online course!)

Short Tandem Repeat DNA Internet Database (STRBase)

DNA Typing — Y-Chromosome Analysis

Several genetic markers have been identified on the Y chromosome that can be used in forensic applications. Y-chromosome markers target only the male fraction of a biological sample. Therefore, this technique can be very valuable if the laboratory detects complex mixtures (multiple male contributors) within a biological evidence sample. Because the Y chromosome is transmitted directly from a father to all of his sons, it can also be used to trace family relationships among males. Advancements in Y-chromosome testing may eventually eliminate the need for laboratories to extract and separate semen and vaginal cells (for example, from a vaginal swab of a rape kit) prior to analysis.

DNA Typing — Mitochondrial Analysis

Mitochondrial DNA (mtDNA) analysis allows forensic laboratories to develop DNA profiles from evidence that may not be suitable for RFLP or STR analysis. While RFLP and PCR techniques analyze DNA extracted from the nucleus of a cell, mtDNA technology analyzes DNA found in a different part of the cell, the mitochondrion (see exhibit 1). Old remains and evidence lacking nucleated cells — such as hair shafts, bones, and teeth — that are unamenable to STR and RFLP testing may yield results if mtDNA analysis is performed. For this reason, mtDNA testing can be very valuable to the investigation of an unsolved case. For example, a cold case log may show that biological evidence in the form of blood, semen, and hair was collected in a particular case, but that all were improperly stored for a long period of time.

Image of Nuclear DNA and Mitochondrial DNA

Although PCR analysis sometimes enables the crime laboratory to generate a DNA profile from very degraded evidence, it is possible that the blood and semen would be so highly degraded that nuclear DNA analysis would not yield a DNA profile. However, the hair shaft could be subjected to mtDNA analysis and thus be the key to solving the case. Finally, it is important to note that all maternal relatives (for example, a person's mother or maternal grandmother) have identical mtDNA. This enables unidentified remains to be analyzed and compared to the mtDNA profile of any maternal relative for the purpose of aiding missing persons or unidentified remains investigations. Although mtDNA analysis can be very valuable to the investigation of criminal cases, laboratory personnel should always be involved in the process.

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DNA101 Part 4 – Possible Results from a DNA Test

Inclusions

When the results obtained from the standard sample from a known individual are all consistent with or are all present in the results from the unknown crime scene sample, then the results are considered an inclusion or nonexclusion. The term "match" is also commonly used when the test results are consistent with the results from a known individual. That individual is included (cannot be excluded) as a possible source of the DNA found in the sample. Often, statistical frequencies regarding the rarity of the particular set of genetic information observed in the unknown evidence sample and for a known individual are provided for various population groups.

It is possible for a falsely accused individual to be included as a source of a sample, particularly if the test system used only tests at one or a few loci (e.g., the DQa). In this situation, additional testing at more loci should be performed with the remaining evidence and/or DNA.

In some cases where inclusions are reported, the results are not meaningful or are inconclusive for that particular case from a legal perspective. Situations where this might apply are when the results obtained are all consistent with the individual from whom the samples were collected (e.g., victim's results only on vaginal swabs taken from the victim, defendant's results only on a bloodstain on defendant's clothing).

Exclusions

When the results obtained from the standard sample from a known individual are not all present in the results from the unknown crime scene sample, the results are considered an exclusion, a nonmatch, or noninclusion. With limited exceptions, an exclusion of an individual at any one genetic region eliminates that individual as a source of the DNA found in the sample.

In some cases where an exclusion is reported, it may be necessary to do additional testing for that exclusion to be meaningful to the case or to provide evidence for exoneration. A situation where this might apply is when the defendant is excluded as a donor of the DNA in a sexual assault case, but no samples are available from the victim and/or consensual partners.

Inconclusive Results

Results may be interpreted as inconclusive for several reasons. These include situations where no results or only partial results are obtained from the sample due to the limited amount of suitable human DNA or where results are obtained from an unknown crime scene sample but there are no samples from known individuals available for comparison. In the latter case, the results would be suitable for comparison once an appropriate sample for comparison is tested.

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DNA101 Part 5 – Types of Samples Suitable for DNA Testing

Questioned or Unknown Samples

Questioned or unknown samples collected from the crime scene can be any biological sample including: liquid blood or bloodstains, liquid saliva or saliva stains, and liquid semen or dried semen stains (including from vasectomized males) deposited on virtually any surface; genital/vaginal/cervical samples collected on swabs or gauze, or as aspirates; rectal/anal swabs; penile swabs; pieces of tissue/skin; fingernails; plucked and shed hairs (e.g., head, pubic, body); skin cells on drinking vessels, clothing (e.g., neck collars, waistbands, hat linings); slides containing tissue, semen, etc.; and liquid urine.

Samples From Unidentified Bodies

Samples collected from unidentified bodies can include: blood, buccal swabs, hairs, bone, teeth, fingernails, tissues from internal organs (including brain), muscle, and skin.

Reference Samples From Known Individuals 

The most common reference samples collected from known individuals are blood, oral/buccal swabs, and/or plucked hairs (e.g., head, pubic).

Samples to Use When No Conventional Reference Samples Are Available 

Other samples that may be considered when individuals are unavailable or are reluctant to provide samples include clothing where biological fluids may be deposited (e.g., women's panty crotches or blood-, saliva-, or semen-stained items) and other clothing in close contact with the body where skin cells may have rubbed off (e.g., collars, waistbands, hats), bedding (with vaginal/semen stains or rubbed off skin cells), fingernail clippings, cigarette butts, toothbrushes, hairs in razors and hairbrushes, discarded facial tissues or handkerchiefs with nasal secretions, condoms, gum, feminine products, pathology paraffin blocks or slides from previous surgery or from autopsy, and teeth.

Reference Samples From Individuals Who Have Been Transfused 

If an individual has received transfusions shortly before the collection of a blood sample (e.g., homicide victim), the DNA test results may indicate the presence of DNA from two or more sources. Generally the predominant DNA types reflect the types from the individual. However, other sources of reference samples for individuals who have received transfusions may need to be collected. These would include: blood-stained clothing or other material (bedding, etc.) and oral, vaginal, and other swabs in addition to the items listed above.

Use of Samples From Relatives for Testing 

Because a child inherits half of its DNA from each parent, it is possible to use reference samples collected from close relatives (e.g., biological father, mother, and/or full siblings or the individual's spouse and their children) to identify or confirm the identity of bodies that have not been identified through other means. It is also possible to use reference samples collected from close relatives for comparison to crime scene samples, for example, in missing body cases where a bloodstain or tissue sample from a possible crime scene can be tested to demonstrate a biological relationship to known individuals.

Determination of Paternity or Maternity of a Child or Fetus 

Aborted fetal tissue can be analyzed for determining paternity, for example, in sexual assault and/or incest cases where conception occurred. Paternity and/or maternity of a child can be confirmed using blood or other samples listed above from the child and the alleged parent(s).

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A Review of DNA Information

Edited by: Don Penven

Back in August 2011 we published the article: What You Should Know About DNA. Not too much has changed since then but a brief review of the highlights of this article and some other material is in order:

 In 1996, Gerald Parker—then in a California prison on a parole violation stemming from a 1980 sentence for raping a child—was charged with the rapes and murders of five women between December 1978 and October 1979 and the murder of a fetus during a rape in 1980. DNA samples from the crime scenes were run through California's sexual assault/violent offender’s database, and four of the cases were found to have been committed by the same perpetrator. After DNA tests linked Parker to the victims, he confessed to the crimes. He also confessed to a similar, fifth crime for which Kevin Lee Green had been wrongly convicted and had served 16 years in prison.

Just as today's law enforcement officer has learned to look routinely for fingerprints to identify the perpetrator of a crime, that same officer needs to think routinely about evidence that may contain DNA. Recent advancements in DNA technology are enabling law enforcement officers to solve cases previously thought to be unsolvable.

Today, investigators with a fundamental knowledge of how to identify, preserve, and collect DNA evidence properly can solve cases in ways previously seen only on television. Evidence invisible to the naked eye can be the key to solving a residential burglary, sexual assault, or a child's murder. It also can be the evidence that links different crime scenes to each other in a small town, within a single State, or even across the Nation.

The saliva on the stamp of a stalker's threatening letter or the skin cells shed on a ligature of a strangled victim can be compared with a suspect's blood or saliva sample. Similarly, DNA collected from the perspiration on a baseball cap discarded by a rapist at one crime scene can be compared with DNA in the saliva swabbed from the bite mark on a different rape victim.

Similar to fingerprints

DNA is similar to fingerprint analysis in how matches are determined. When using either DNA or a fingerprint to identify a suspect, the evidence collected from the crime scene is compared with the "known" print. If enough of the identifying features are the same, the DNA or fingerprint is determined to be a match. If, however, even one feature of the DNA or fingerprint is different, it is determined not to have come from that suspect.

What Is DNA?

DNA, or deoxyribonucleic acid, is the fundamental building block for an individual's entire genetic makeup. It is a component of virtually every cell in the human body. Further, a person's DNA is the same in every cell. For example, the DNA in a man's blood is the same as the DNA in his skin cells, semen, and saliva.

DNA is a powerful tool because each person's DNA is different from every other individual's, except for identical twins. Because of that difference, DNA collected from a crime scene can either link a suspect to the evidence or eliminate a suspect, similar to the use of fingerprints. It also can identify a victim through DNA from relatives, even when no body can be found. And when evidence from one crime scene is compared with evidence from another, those crime scenes can be linked to the same perpetrator locally, statewide, and across the Nation.

Forensically valuable DNA can be found on evidence that is decades old. However, several factors can affect the DNA left at a crime scene, including environmental factors (e.g., heat, sunlight, moisture, bacteria, and mold). Therefore, not all DNA evidence will result in a usable DNA profile. Further, just like fingerprints, DNA testing cannot tell officers when the suspect was at the crime scene or for how long.

Where can DNA evidence be found at a crime scene?

DNA evidence can be collected from virtually anywhere. DNA has helped solve many cases when imaginative investigators collected evidence from nontraditional sources. One murder was solved when the suspect's DNA, taken from saliva in a dental impression mold, matched the DNA swabbed from a bite mark on the victim. A masked rapist was convicted of forced oral copulation when his victim's DNA matched DNA swabbed from the suspect's penis 6 hours after the offense. Numerous cases have be been solved by DNA analysis of saliva on cigarette butts, postage stamps, and the area around the mouth opening on ski masks. DNA analysis of a single hair (without the root) found deep in the victim's throat provided a critical piece of evidence used in a capital murder conviction.

Evidence Collection and Preservation

Crime Scene Investigators and laboratory personnel should work together to determine the most probative pieces of evidence and to establish priorities. Although this article is not intended as a manual for DNA evidence collection, every officer should be aware of important issues involved in the identification, collection, transportation, and storage of DNA evidence.

What is PCR

(Wikipedia:) The polymerase chain reaction (PCR) is a biochemical technology in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.

Developed in 1983 by Kary Mullis, PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. These include DNA cloning for sequencing, DNA-based phylogeny, or functional analysis of genes; the diagnosis of hereditary diseases; the identification of genetic fingerprints (used in forensic sciences and paternity testing); and the detection and diagnosis of infectious diseases. In 1993, Mullis was awarded the Nobel Prize in Chemistry along with Michael Smith for his work on PCR.

The method relies on thermal cycling, consisting of cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA. Primers (short DNA fragments) containing sequences complementary to the target region along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification. As PCR progresses, the DNA generated is itself used as a template for replication, setting in motion a chain reaction in which the DNA template is exponentially amplified. PCR can be extensively modified to perform a wide array of genetic manipulations.

Almost all PCR applications employ a heat-stable DNA polymerase, such as Taq polymerase, an enzyme originally isolated from the bacterium Thermus aquaticus. This DNA polymerase enzymatically assembles a new DNA strand from DNA building-blocks, the nucleotides, by using single-stranded DNA as a template and DNA oligonucleotides (also called DNA primers), which are required for initiation of DNA synthesis. The vast majority of PCR methods use thermal cycling, i.e., alternately heating and cooling the PCR sample through a defined series of temperature steps. In the first step, the two strands of the DNA double helix are physically separated at a high temperature in a process called DNA melting. In the second step, the temperature is lowered and the two DNA strands become templates for DNA polymerase to selectively amplify the target DNA. The selectivity of PCR results from the use of primers that are complementary to the DNA region targeted for amplification under specific thermal cycling conditions.

We believe that DNA is of such great importance to criminal investigation that we have created a separate blog category, DNA at Crime Scenes, in order for our readers to have a readily-available section for information on this vital subject. Plan to check back often for updated information.

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Eyewitness Identification Reforms May Have Unintended Consequences

UC Riverside, May 30, 2012

New research by a University of California, Riverside psychologist raises serious questions about eyewitness identification procedures that are being adopted by police departments across the United States.

These new procedures are designed to reduce the kinds of false identification errors that can lead to wrongful convictions of innocent people.

While it has long been held that these changes reduce false identifications with little or no loss of correct identifications, UC Riverside psychology professor Steven E. Clark suggests that that is not the case.

The loss of correct identifications can be significant, Clark says. Importantly, the new procedures may, under some circumstances, lead to identification evidence that is less accurate than the identification evidence from the procedures they are designed to replace. Policymakers need to look very carefully at the data from empirical studies as they consider adopting new procedures, he cautions.

Clark's study, "Costs and Benefits of Eyewitness Identification Reform: Psychological Science and public Policy," appears in the May issue of the peer-reviewed journal Perspectives on Psychological Science, published by the Association for Psychological Science.

Clark has been involved in more than 200 criminal and civil cases, has consulted with prosecution and defense attorneys, and has testified as an expert in federal and state courts in six states, including California. Much of his research has been funded by the National Science Foundation.

In the paper, the psychologist notes that the reforms are directed at fundamental aspects of the identification process: How lineups are constructed, what witnesses are told and how they are instructed prior to the lineup, the way that the lineup is presented, and what police officers should and should not say and do during the identification procedure.

"Whether policymakers decide to adopt or not adopt these new procedures is up to them," he says. "In order to make those policy decisions, they need to know clearly what the benefits are and what the costs are."

For some of the new procedures the cost-benefit trade-offs are clear. For other procedures, Clark suggests that the critical research has not been done. For example, one of the new procedures coming into use requires that the police officer who shows the lineup not know which person in the lineup is the suspect. In this "blind" procedure, the police officer would not know whether the suspect was second, third or sixth in the lineup. The blind procedure prevents police officers from deliberately or inadvertently cuing witnesses about who they should pick from the lineup.

"The principle behind blind lineup administration is solid," Clark says. "If the criminal justice system is concerned that the police might inadvertently communicate their expectations to witnesses, then a good solution is for the police to not have expectations by not knowing which person in the lineup is the suspect. However, many ideas that seem right in principle don't actually work, or have unintended side effects. The principle behind the blind lineup may be solid, but solid data would be better."

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Officer Survival: Badge Grab - Defensive Tactics Technique

Watch, listen and learn as Defensive Tactics instructor Richard Nance talks about the perils of someone grabbing your badge and some simple, easy techniques you can use to mitigate the threat.

Badge Grab Video

 

 

 

Officer Survival Tips-Missing Danger Signs

Officer Survival Videos:

The Missing Danger Signs, Officer Dave Smith—Officer Survival Instructor Dave Smith, aka JD Buck Savage, discusses one of the 10 deadly errors: Missing danger signs.

The Missing Danger Signs

Sirchie’s commitment to crime scene investigation training

Committed to providing high quality forensic science and criminal investigation training, Sirchie’s Education and Training Division offers a variety of courses structured to meet the global law enforcement community's and each student’s particular needs.  There are several options we make available to you to acquire the training you need.

These options include:

Distance Learning: The American Institute of Applied Science Distance Education Program offers home study correspondence courses in criminology and basic forensics

On-Site Training:

Sirchie's dedicated training facility located at our campus in Youngsville, NC

Comprehensive “hands-on” Evidence Collection Courses.

Sirchie-sponsored crime scene related courses including Bloodstain Pattern Documentation and Crime Scene Photography- Phase 1

Fingerprint Classification and Comparison Courses including:

• Introduction to the Science of Fingerprints
• Latent Fingerprint Comparison
• Advanced Latent Ridgeology
• Latent Palm Print Comparison
• Mastering the "Comparison Phase" of the IAI Certification Exam

Customized Crime Scene and Evidence Collection Courses for domestic and international customers.  Sirchie will work with you to deliver our courses at a convenient location for your organization.

Please note: The remaining dates for the 2013 Crime Scene Technology Training Program are fully booked. Please call and request information on dates available for 2014.

Please contact us at [email protected] or call the Training Coordinator at 1-800-356-7311

Family Firearm Safety: Officer Survival Tip

Watch, listen and learn from the legendary JD "Buck" Savage (internationally known trainer, Lt. Dave Smith (ret) ) as he discusses firearms safety where you and your family are concerned.

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A serious look inside crime scene investigation

By Prue Bentley , http://realtime.rediff.com

CSI might have made forensics glamorous but the truth is far

more interesting.

 In a suburban home a young man lies dead in a pool of blood.

Above him on the wall is a bloody hand print, empty bullet casings litter the floor and there's a metal bar by his head.

A drug lab lies idle in the back room and there's an empty space in the kitchen knife block.

It sounds like the scene from a crime drama but it's actually a simulation for forensic science students at Deakin University.

At the university's Waurn Ponds campus they're preparing the next generation of forensic crime scene experts.

Generally, short of going out with police there's not a lot of opportunity for students to get hands on experience of working in a crime scene.

So they've established a Forensic Crime Scene Training Centre that tests students' skills of observation and forensic evidence gathering.

Dr Xavier Conlin is a Senior Lecturer in Forensic Science and while walking through the murder scenario he stresses that in this kind of circumstance it's hard to know what could be evidence and what's effectively a red herring.

"If there's a missing knife it may not have been used in terms of the murder that we've seen but there may be fingerprints from a perpetrator."

Dr Michelle Harvey is the Course Director and an expert in forensic entomology, or the charming world of maggots.

She explains that after a person dies flies are attracted to the odours it emits and lay their eggs in the wounds, the age of the insects are then used to estimate the time of death.

"I think it's fascinating to take the humble Aussie blowfly that most people hate and put it to good use."

Mock scenes like this also provide a great environment for students to practise crime scene safety.

David Donaldson is a PHD student in Forensic Science at Deakin with a focus on explosives.

He says he was drawn to the profession after seeing CSI on TV but once he arrived in the course he was "told specifically the course wasn't going to be like that" mostly because they didn't yet have a facility like their new Training Centre.

Now though he's able to practice in the field what he's learning in the classroom.

As he's getting into his blue, protective onesie he explains equipment like this is as much to protect him as it is the crime scene.

"You want to keep everything that's on your person, on your person, you don't want to bring anything in so you want to try and handle the outside as little as possible... we are dealing with fine particulate powders. I don't want to breathe anything in from the crime scene and I also don't want to put my own saliva and DNA all over the scene."

Once the lights go out and the UV equipment comes out to check for invisible fluids, the scene is looking more and more like something from TV.

But Dr Harvey explains the difference between fiction and reality is still pretty stark.

"Some of your tests that you might have to do in the lab could take weeks to months and then there's a waiting process where you're preparing the case and having to move through the legal system so everything doesn't necessarily happen in a day, there are cases that are not going to be solved for 20 or 30 years... you might have to wait until you've got new technology to be able to do some kind of analysis.

Ultimately the truth comes out. I teach my students there's no such thing as a perfect murder.

"Everyone gets caught."

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When You Lie, Your Nose Temperature Rises: The Pinocchio Effect

Science Daily  

When a person lies, they experience a "Pinocchio effect," which is an increase in the temperature around the nose and in the orbital muscle in the inner corner of the eye. In addition, when we perform a considerable mental effort our face temperature drops, and when we have an anxiety attack our face temperature rises. These are some of the conclusions drawn in a pioneering study conducted at the University of Granada Department of Experimental Psychology, which has introduced new applications of thermography.

Thermography is a technique based on body temperature that is applied in many fields such as general industry, the building industry and medicine. Thermographic cameras have a wide range of uses such as measuring energy loss in buildings, indicating respiratory diseases in bovine animals or rabies in raccoons. Thermography was developed in the USA during the II World War to detect the enemy (night vision).

Excitement is the Same in Men and Women

The University of Granada researchers Emilio Gómez Milán and Elvira Salazar López have been pioneers in applying thermography to the field of Psychology, and they have obtained very innovative and interesting results. Sexual excitement and desire can be identified in men and women using thermography, since they induce an increase in chest and genital temperature. This study demonstrates that -- in physiological terms -- men and women get excited at the same time, even although women say they are not excited or only slightly excited.

Scientists have discovered that when a mental effort is made (performing difficult tasks, being interrogated on a specific event or lying) face temperature changes.

When we lie about our feelings, the temperature around our nose raises and a brain element called "insula" is activated. The insula is a component of the brain reward system, and it only activates when we experience real feelings (called "qualias"). The insula is involved in the detection and regulation of body temperature. Therefore, there is a strong negative correlation between insula activity and temperature increase: the more active the insule (the greater the feeling) the lower the temperature change, and vice versa, the researchers state.

The Thermal Footprint of Flamenco

Researchers also determined the thermal footprint of aerobic exercise and different dance modalities such as ballet. When a person is dancing flamenco the temperature in their buttocks drops and it increases in their forearms. That is the thermal footprint of flamenco, and each dance modality has a specific thermal footprint, professor Salazar explains.

The researchers have demonstrated that temperature asymmetries in both sides of the body and local temperature changes are associated with the physical, mental and emotional status of the subject. The thermogram is a somatic marker of subjective or mental states and allows us see what a person is feeling or thinking, professor Salazar states.

Finally, thermography is useful for evaluating emotions (since the face thermal pattern is different) and identifying emotional contagion. For example, when a highly empathic person sees another person having an electric discharge in their forearm, they become infected by their suffering and temperature in their forearm increases. In patients with certain neurological disease such as multiple sclerosis, the body does not properly regulates temperature, which can be detected by a thermogram. Thermography can also be applied to determine body fat patterns, which is very useful in weight loss and training programs. It can also be applied to assess body temperature in celiac patients and in patients with anorexia, etc.

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Entomology at The Crime Scene--Insect Studies

Invasive Fly Species Continues to Move Northward

Science Daily 

July 2, 2013 — The local discovery of a species of fly not native to the Midwest could have significant implications on forensic investigations involving decomposing remains, according to a forensic biology researcher at Indiana University-Purdue University Indianapolis (IUPUI).

Christine Picard, Ph.D., assistant professor of biology in the School of Science at IUPUI,
discovered the fly, Chrysomya megacephala Fabricius (C. megacephala), during a routine collection of fly samples in late September 2012. Until now, entomologists had never documented the fly farther north than New Mexico.

"Although I only found a single fly of this species, this is an important event in the area of forensics," said Picard, also a faculty member in the Forensic and Investigative Sciences program at IUPUI. "Because this fly is not typically found here, we don't know how it develops here, how to use that data or how it could affect the precision and accuracy of forensic investigations."

The growth and development of flies play an important role for scientists looking to learn how long a human or other animal has been dead. When a new species is introduced, scientists or investigators may be at a disadvantage because of the little data that exists locally on that species.

C. megacephala breeds in the decomposing flesh of animals or discarded organic materials and has the potential to carry disease. Its existence could negatively impact the native species of flies as well, changing the dynamics of this highly specialized ecosystem.

"This discovery tells us as researchers that there is a new fly we have to consider, especially when we're processing casework samples." Picard said.

The fly specimen currently is stored at the Purdue University Entomological Collection, and it is the only one of its kind in its vast inventory. Picard's discovery will be published in the July edition of the Proceedings of the Entomological Society of Washington journal.

This particular fly, native to Asia and Africa, first was documented in 1988 in the United States. Until now, it had been contained to the southern states, where the warmer climate allows it to grow and breed. The mild winter and long, drought-stricken summer of 2012 in Indiana likely contributed to the fly moving this far north, Picard said.

As average temperatures continue to increase, Picard predicts this will not be the last time Indiana sees this fly.

"This fly has the potential to become a dominant fly species in this area," Picard said. "The changing climate conditions show us that we should never really stop collecting samples. We will be on the lookout this summer for more of this particular fly."

This new fly species, Chrysomya Megacephala, is not native to Indiana but was found last fall in Indianapolis. Its discovery could impact forensic investigations. (Credit: Image courtesy of Indiana University-Purdue University Indianapolis School of Science)

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Enhancing of Blood Prints on Washed Clothing Using Luminol and LCV Reagents

Thomas W. Adair and Rebecca L. Shaw

Introduction:

Luminol and LCV are commonly used reagents to develop latent bloodstains on evidence and at crime scenes. Luminol was first used to detect latent bloodstains in 1937 (1). Since that time the use of luminol has become very popular with many law enforcement agencies. The application of luminol creates a blue/green color chemiluminescence from its reaction with hemoglobin. Observation and subsequent documentation of latent bloodstain reactions with luminol require near to total darkness for best results. Leuco-crystal Violet (LCV) is another commonly used latent blood reagent for evidence and crime scenes. Bodziak (2) reports that the Federal Bureau of Investigation laboratory has utilized LCV since 1993. Like luminol, the application of LCV to latent bloodstains creates a catalytic reaction with hemoglobin. Unlike luminol, however, the LCV reaction is visible in normal lighting. LCV stains latent blood a dark purple to black color allowing for easy observation and documentation on light colored surfaces. Bodziak does caution that visible bloodstains on fabric are best processed with DAB or Amido Black reagents.

This research investigates the use of luminol and LCV to develop latent bloodstains from clothing, which has been washed with a commonly available cleaning product. A second aspect of this research was to test the use of the phenolphthalein as a presumptive blood test on the washed clothing items. A search of the major English language forensic journals and textbooks relating to bloodstain pattern analysis did not reveal any study that specifically examined the use of reagents on washed clothing. Quickenden et. al. (3) conducted research on the effectiveness of luminol in detecting washed bloodstains from automobile interiors. One interesting observation of their experiments was the conversion of hemoglobin to methemoglobin from increased heat in the motor vehicle following the deposition of blood. This resulted in and increased (enhanced) sensitivity of the luminol reaction. Not surprisingly, the authors discovered that repeated washings of interior surfaces decreased the sensitivity of the luminol reaction compared to non-washed surfaces. The authors did note, however, that the cleaning of carpet with a water and soap solution removed only the surface staining, leaving a strong presence within the foam padding of carpeting. Large quantitative differences in luminol reaction were observed between various carpet styles and commercial cleaning solutions however. Creamer et. al. (4) conducted research to determine the effect of the luminol reaction following the use of a known interfering catalyst (bleach) on washed items. The authors noted that luminol is highly sensitive, capable of detecting nanogram traces of blood. While their experiments were conducted on nonporous ceramic tiles, they observed that interference from bleach dissipated after approximately eight hours. DeHaan et. al. (5) also conducted sensitivity experiments with LCV on both porous and non-porous surfaces. Their research indicated LCV could detect blood at a dilution of 1:10,000, considerably less than luminol.

Gifford (6) reported a case study in which bloodstains were found on the clothing of a male victim who had been discovered in water six days following his death. The author conducted experiments on bloodstained clothing in moving and stagnant water and found that bloodstains would not remain on the clothing after 30 minutes in moving water and not more than three hours in stagnant water. Certainly the action of the washing machine will dissipate blood at an even faster rate. Following his experiments, Gifford concluded that diffused blood still visible on the victim’s wet or washed clothing was deposited after the clothing was removed from the water source (in that case a stream).

Materials and Testing Methods: 

All experiments were conducted at the Arapahoe County Sheriff’s Office Crime Laboratory in Centennial, Colorado in July of 2005. Whole horse blood obtained from a local veterinarian hospital was used for all experiments. Quickenden and Cooper (7) experimented with the luminol reaction using both human and bovine hemoglobin and found no significant difference in luminol reactions. Ten white colored Haynes brand “signature collection” 100% cotton undershirts were used for these experiments. The shirts had been worn for approximately 6-8 months prior to experimentation but had not previously been stained with blood. There was no visible discoloration or staining in the testing areas prior to the experiments. An eleventh shirt of the same condition was used as a control. The shirts were labeled #1-11 near the neckline with a black Sharpie brand marker (designations “B” and “F” for back and front). Three different types of bloodstain patterns were produced on both the front and back of each shirt (Figure 1).

 

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