By: Dr. Thomas O’Connor
Program Manager of Criminal Justice and Homeland Security
Director, Institute for Global Security Studies
Austin Peay State University
601 College Street
Clarksville, TN 37044
http://www.drtomoconnor.com/3220/3220lect03.htm
Any investigation into the world of violent crime, such as homicide, suicide, and sex offenses, carries with it some standard procedures of analysis and reconstruction, which we'll discuss here in the context of fairly typical and uncomplicated (exemplar or unequivocal) crime scenes. There are a few similarities as well as differences with the crime of arson (sometimes treated a violent crime), but the homicide exemplar is so typical of the investigative process as a whole that it's often the only corpus delicti a student needs to know in learning how to investigate (Axelrod & Antinozzi 2003). Many of the skills involved in conducting a homicide investigation carry over into other crimes, not all, but many. Homicide is therefore considered an exemplar, or good example, to use in the teaching of criminal investigation. Homicide involves both the study of victimology and suspectology.
A few caveats are in order before we begin. One such caveat has to do with the necessity of speed or haste. A homicide needs to be investigated quickly because information and evidence will often lose its freshness and become tainted in short order. Another caveat is that just because you find a body at the crime scene doesn't mean you should launch a homicide investigation. Homicide is only the sixth leading cause of death in America. The following table illustrates the odds for average Americans:
|
Cause of Death |
Odds of Occurrence |
|
Disease |
1 in 1.3 |
There are times when a preliminary walk-through will tell you that the death is by natural or accidental causes (the top four causes of death), but as a general rule, you should treat all apparent suicides as homicides at first. With suicides, you may or may not find a note left behind for loved ones, but if you do, you should treat it as a questioned document. A suicide can, of course, also be accidental or intentional. The most common accidental ones involve misuse of firearms and drugs. The most common intentional ones involve hanging and jumping (although sexual asphyxiation is usually classified as accidental). The special case of drowning is equally likely to be either accidental or intentional. The following table lists the most frequent order of occurrence for intentional suicides along with a rank order of the most damaging life stressors:
|
Intentional Suicides |
Most Serious Stressors |
|
1. Hanging |
1. Death of spouse |
With homicides, a good rule to follow is make the arrest within 72 hours or the chances of ever making it plummet (Morn 2000). Another caveat is that it is not absolutely necessary to have a body to launch a homicide investigation. Missing persons situations are somewhat special, and you should refer to your department's policies on that, but in most cases when you suspect a homicide, it probably is a homicide, and when you suspect an abduction, it probably is an abduction. If you can't find the body, it's most likely buried or underwater somewhere, unless you're dealing with kidnapping, serial killing, or sexual cannibalism (O'Connor 2001). Remember that insects and animals will eat up about 60% of the corpse within a week, and unless they are weighted down or stuck on an underwater eddy obstruction, sunken bodies usually become "floaters" by the end of a week.
HOMICIDE INVESTIGATION
Our society does a pretty good job of tracking dead people and determining criminal causes of death. There's only about 25,000 homicides a year, and you can probably have some confidence in that number as an accurate figure representing the real number of homicides every year.
Homicide is a crime with a pretty high clearance rate; at least 65% of all homicides are solved by arrest of the perpetrator, and some years, the percentage is closer to 85%. Guns, alcohol, drugs, love, felony-murder, blunt force trauma, knife fights, and strangulation are all associated with homicide. The LAW of homicide needs to be clearly understood:
- 1st degree (cold-blooded murder) requires proof of premeditation, deliberation, and malice (planning, coolness, scheming)
- 2nd degree (hot-blooded murder) requires proof of malice aforethought and intent to do bodily harm (for all practical purposes, malice aforethought is the same as premeditation)
- Voluntary manslaughter (heat of passion) requires proof of provocation and no time to cool off (self-defense is a common defense)
- Involuntary manslaughter (accidents) require at least a reckless disregard of the consequences (insanity is a common defense)
Treat all cases of death that you come across as a homicide at first, even suicides. Remember that motive, circumstance, and purpose are key elements in determining exactly what type of homicide you're investigating. Be prepared for self-defense and insanity claims. Look at the crime scene for evidence of passion, provocation, and signs of struggle. Analyze the wound patterns, and try to reconstruct what happened from the fingerprints, bloodstains, and ballistics.
TAKING THE CALL
It's important to appreciate how death comes to the attention of police, and more importantly, how the case happens to come across your desk. Chances are that someone you know or something you already know about is related to the case, so there's going to be a linkage between this case and one or more of your other cases or something in the police files, like repeated calls for service to an address for domestic problems. You definitely want to know who called the police and exactly when they called and what their voice sounded like over the telephone. A linguistic analysis might be helpful. You might also want to think about initially consulting with others in your department about what they suspect, but it's best to keep an open mind.
ARRIVING AT THE SCENE
If you are the first responder (not likely), then exercise procedures called for in the acronym ADAPT (Assess scene, Detain witnesses, Arrest perpetrator, Protect scene, and Take notes). If the victim is still dying, then take their dying declaration. This is compelling courtroom evidence. To be admissible, the victim must believe their death is imminent, and what they say must specifically concern the cause or circumstances they believe about their impending death. If the victim is apparently dead, determine if they are really dead and/or attempt resuscitation. Here's the legal signs of death:
- no respiration
- no heartbeat
- no pulse
- fingernails don't flush when pressed
- eyelids don't close when lifted
- no pupil dilation to light
If the dead person is missing, ask any witnesses if they know where the body might be. If paramedics, the coroner's office, or Medical Examiner took it, remember that they "own" the body, but you control the crime scene. Use witness accounts to put chalk lines down where the body was. Start note taking on characteristics having to do with BODY location, then turn to likely entry and exit points. Secure the scene after that, and then record your own movements. If night is falling, and the scene is dark, call the fire department because they usually have excellent lighting equipment.
IDENTIFYING THE VICTIM
The body of a dead person is like an encyclopedia of information and knowledge, if only you know how to read it. The thing to remember is always corroborate, and double-check your identification sources. Don't assume the ID in the victim's wallet isn't a planted ID. Assume that everyone at the crime scene is going to lie to you. There will be the usual cast of characters, and some of them will be serious jokers while others are joking seriously. Confiscate all personal effects of the victim. Look at the victim's clothing and body for stains, laundry marks, monograms, tattoos, etc. Be mindful of planted evidence. Take pictures (facial shots, if not too graphic) and get a family member or somebody to ID the person (if not too graphic). Order fingerprinting, DNA tests, dental X-rays, forensic anthropology on the bones, or whatever you need to do in identifying the body. As a last resort, release a composite sketch to the media: "Do You Know This Person?"
ESTIMATING THE TIME OF DEATH
There's always going to be at least two (2) estimates of the time of death -- the police department's official estimate (which may or may not be yours) and the Medical Examiner's estimate. Legally, you should be within 4 hours of being accurate, but this is a tough standard even for the best coroners. Remember that, after death, the body starts to cool down to whatever the outside (or room) temperature is. At death, the body starts to drop from it's normal 98.6 degrees by a factor of 3 degrees the first hour and a factor of 1 degree each subsequent hour. Then, after 30 hours, it starts to go up again because of the heat generated by decomposition (but this varies by room or outside temperature, so you need to know weather conditions). The following table illustrates:
- 98.6 - time of death
- 95.6 - one hour after death
- 94.6 - two hours after death
- 93.6 - three hours after death
- 92.6 - four hours after death
- 91.6 - five hours after death
- 90.6 - six hours after death
- -------- (to room or outside temp.)
- 66.6 - thirty hours after death
- 67.6 - thirty-one hours after death
- 68.6 - thirty-two hours after death
- 69.6 - thirty-three hours after death
- -------- (to room or outside temp.)
Rigor mortis is also something you should know about. The body is limp until about 5-6 hours after death, then a hardness begins to set in around the jaw area in front of the ear (temporal mandibular joint area). It then spreads throughout the body for a period of time, and then the body goes limp again. The following chart illustrates:
- stiffness in jaw -- 6 hours after death
- stiffness in upper torso -- 12 hours after death
- stiffness in whole body -- 18 hours after death
- limpness returns to body -- 36 hours after death
Lividity is the effect of gravity on blood. You'll note that after death, all the loose blood in the body runs down to the lowest point of gravity. If the dead person is on their back, you'll notice these bluish-purple stains on their back. Lividity begins after only 3 hours, and the blood becomes dried after only 12 hours, so lividity is something to look for quick. It tells you if the body has been moved or transported when there are lividity marks in unusual places instead of the lowest point of gravity where you find the body. You can distinguish lividity from a bruise by pressing down on the skin area. Since with lividity, the blood is still in the blood vessels, when you press down on the skin, the skin changes color and turns white (or whatever skin color the person normally has). Bruises, by definition, are broken blood vessels, so when you press down on the skin area for them, you won't notice any color change; the skin area will just turn another shade of bluish-green.
The eyes dilate 7 hours after death (dilation is enlargement of the black pupil area). Drugs will also create unusual eye dilations, as will certain poisons, although breath odor is the more likely place to look for poison. After 12 hours, the whole eye gets cloudy and fish-like. If the person is disemboweled or has thrown up, look at the stomach contents. Anything eaten in the last 2 hours is undigested; food spends 6 hours in the small intestine and 12 hours in the large intestine. If your victim has been underwater, the average dead person sinks for about 8-10 days (depending on body weight), then they become "floaters" on about the 11th day (although a light person might float after only 7 days).
Decomposition begins in 30 hours and then starts to rise rapidly after 48 hours. The soapy, mushy remains of a body indicate they've been dead for 3 months. If they are partially mummified, they've been dead for a year. Decomposition is unmistakable by it's smell (the smell of death). You'll be able to see the gases coming out of small gas blisters all over the body, and you won't be able to overlook that bloated greenish tint that the whole body has.
If it's an outdoor crime scene, chances are that small animals have eaten or carried off parts of the body, and even with indoor crime scenes, you're going to have the problem of insects (it wouldn't hurt to know some entomology). North America is home to a particular species (Calliphoridae) of fly known as the blow fly, and they love to lay their eggs on the bodies of dead humans. You'll probably discover bodies teeming with maggots (fly larvae). If you can locate the largest (oldest maggot), measure it in millimeters and add the number two (2), you'll have the approximate number of days since death. A comprehensive checklist of things for determining the time of death would include the following:
1. the temperature of the body and the rate of cooling
2. the degree of postmortem lividity (hypostasis)
3. the degree of rigor mortis
4. putrefaction
5. insect activity
6. analyzing stomach contents
ESTIMATING THE CAUSE OF DEATH
Look at the body, how it's posed. Look at the wounds. Look for defensive marks on the knuckles or pieces of skin under the fingernails, anything that might indicate a struggle ensued. Examine the skin’s surfaces for wounds, pinpricks, needle marks. Look to see if anything's in the mouth, vagina, or rectal areas. If your victim's been raped, do a pubic hair combing. Bag & tag any traces of fluids. If your victim's been strangled, determine if there are any ligature marks. Strangulation marks are horizontal around the neck, and hanging marks are on an upward angle to the back of the head. Determine any poisoning or drugs from odors, color of lips, toes and fingernails.
The facial expression may tell you something or it may not (most of the time not, as upon death, the facial muscles relax and it is virtually impossible to determine what caused the death). Experienced investigators have marveled over the peaceful countenance of victims who have undergone horribly painful deaths. Nevertheless, there are some possibilities that you can go by as long as you realize we're treading more on myth than science here. Death by firearms may result in a shocked look of expression on the face. After all, that's what you die from in a gunshot injury: shock, either that, or they hit a vital organ. A strangulation death may have a gasping for air look.
A blunt force trauma death may have a more painful than peaceful look. A knife or bleeding death may involve a fairly relaxed look. A drug overdose may be likely to involve a smile on the face, and some types of poisonings (strychnine) produce such violent convulsions that the back arches and this causes the facial muscles to contort into a sardonic grin. In reality, however, it is unlikely that you will be able to make estimates from facial expression, since this is not a sound method of investigation. When death occurs, the muscles relax, and are especially more relaxed by the time you look at the body in the morgue.
If you know bloodstains or ballistics, conduct an analysis of angle and points of trajectory. Look around for the murder weapon. It might be down the point of exit. The coroner's report may or may not be of any use to you. Often, they are full of medical jargon about the mechanism, not the cause, of death.
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