High-Tech, High-Risk Forensics
By OSAGIE K.
OBASOGIE, NY
Times
SAN
FRANCISCO — WHEN the police arrived last November at the ransacked mansion of
the millionaire investor Raveesh Kumra, outside of San Jose, Calif., they found
Mr. Kumra had been blindfolded, tied and gagged. The robbers took cash, rare
coins and ultimately Mr. Kumra’s life; he died at the scene, suffocated by the
packaging tape used to stifle his screams. A forensics team found DNA on his
fingernails that belonged to an unknown person, presumably one of the
assailants. The sample was put into a DNA database and turned up a “hit” — a
local man by the name of Lukis Anderson.
Bingo. Mr.
Anderson was arrested and charged with murder.
There was
one small problem: the 26-year-old Mr. Anderson couldn’t have been the culprit.
During the night in question, he was at the Santa Clara Valley Medical Center,
suffering from severe intoxication.
Yet he spent
more than five months in jail with a possible death sentence hanging over his
head. Once presented with Mr. Anderson’s hospital records, prosecutors
struggled to figure out how an innocent man’s DNA could have ended up on a
murder victim.
Late last
month, prosecutors announced what they believe to be the answer: the paramedics
who transported Mr. Anderson to the hospital were the very same individuals who
responded to the crime scene at the mansion a few hours later. Prosecutors now
conclude that at some point, Mr. Anderson’s DNA must have been accidentally
transferred to Mr. Kumra’s body — likely by way of the paramedics’ clothing or
equipment.
This theory
of transference is still under investigation. Nevertheless, the certainty with
which prosecutors charged Mr. Anderson with murder highlights the very real
injustices that can occur when we place too much faith in DNA forensic
technologies.
In the end,
Mr. Anderson was lucky. His alibi was rock solid; prosecutors were forced to
concede that there must have been some other explanation. It’s hard to believe
that, out of the growing number of convictions based largely or exclusively on
DNA evidence, there haven’t been any similar mistakes.
In one
famous case of crime scene contamination, German police searched for around 15
years for a serial killer they called the “Phantom of Heilbronn” — an unknown
female linked by traces of DNA to six murders across Germany and Austria. In
2009, the police found their “suspect”: a worker at a factory that produced the
cotton swabs police used in their investigations had been accidentally contaminating
them with her own DNA.
Contamination
is not the only way DNA forensics can lead to injustice. Consider the frequent
claim that it is highly unlikely, if not impossible, for two DNA profiles to
match by coincidence. A 2005 audit of Arizona’s DNA database showed that, out
of some 65,000 profiles, nearly 150 pairs matched at a level typically
considered high enough to identify and prosecute suspects. Yet these profiles
were clearly from different people.
There are
also problems with the way DNA evidence is interpreted and presented to juries.
In 2008, John Puckett — a California man in his 70s with a sexual assault
record — was accused of a 1972 killing, after a trawl of the state database
partially linked his DNA to crime scene evidence. As in the Anderson case, Mr.
Puckett was identified and implicated primarily by this evidence. Jurors — told
that there was only a one-in-1.1 million chance that this DNA match was pure
coincidence — convicted him. He is now serving a life sentence.
But that
one-in-1.1 million figure is misleading, according to two different expert
committees, one convened by the F.B.I., the other by the National Research
Council. It reflects the chance of a coincidental match in relation to the size
of the general population (assuming that the suspect is the only one examined
and is not related to the real culprit). Instead of the general population, we
should be looking at only the number of profiles in the DNA database. Taking
the size of the database into account in Mr. Puckett’s case (and, again,
assuming the real culprit’s profile is not in the database) would have led to a
dramatic change in the estimate, to one in three.
One juror
was asked whether this figure would have affected the jury’s deliberations. “Of
course it would have changed things,” he told reporters. “It would have changed
a lot of things.”
DNA
forensics is an invaluable tool for law enforcement. But it is most useful when
it corroborates other evidence pointing to a suspect, or when used to determine
whether any two individual samples match, like in the exonerations pursued by
the Innocence Project.
But when the
government gets into the business of warehousing millions of DNA profiles to
seek “cold hits” as the primary basis for prosecutions, much more oversight by
and accountability to the public is warranted. For far too long, we have
allowed the myth of DNA infallibility to chip away at our skepticism of
government’s prosecutorial power, undoubtedly leading to untold injustices.
In the
Anderson case, thankfully, prosecutors acknowledged the obvious: their suspect
could not have been in two places at once. But he was dangerously close to
being on his way to death row because of that speck of DNA. That one piece of
evidence — obtained from a technology with known limitations, and susceptible
to human error and prosecutorial misuse — might mistakenly lead to execution at
the hands of the state should send chills down every one of our spines. The
next Lukis Anderson could be you. Better hope your alibi is as well documented
as his.
Osagie K.
Obasogie, a professor of law at the University of California, Hastings, and a
senior fellow at the Center for Genetics and Society, is the author of the
forthcoming book “Blinded by Sight: Seeing Race Through the Eyes of the Blind.”
