Forensics On Trial
measl at mfn.org
Sun Feb 20 12:08:08 PST 2011
Forensics Under the Microscope
More courts are starting to question the .facts. proved by scientific
Warren Horinek did not murder his wife. That.s what he said, that.s what
the medical examiner said, that.s what the homicide sergeant said. Even
the district attorney.s office in the Horineks. hometown of Ft. Worth,
Texas, agreed that he was innocent.not something a Texas prosecutor
typically says. But when Bonnie Horinek died in 1995, her parents refused
to believe what the evidence strongly suggested.that Bonnie shot
herself.and instead they enlisted the services of a blood-spatter analyst
to prove that it was their son-in-law who had killed their daughter.
The spatter analyst zeroed in on the blood-soaked T shirt Horinek was
wearing when the paramedics arrived. To him, the fine spray of blood on
Horinek.s left shoulder was not from administering CPR, as Warren said it
was, and as the 911 recording seemed to indicate, but from shooting Bonnie
at close range. On the basis of that testimony, Horinek was convicted of
murder and sentenced to 30 years. But did they really get their man?
Horinek.s lawyers have filed a writ of habeas corpus to try to have him
released, based in part on the National Academy.s report; much of the
spatter analyst.s testimony, the lawyers argue, .was contrary to known and
In the age of CSI and Dexter, we.re led to believe that forensic science
is a high-tech discipline, powerful and sophisticated enough to catch any
As it turns out, whether blood-spatter analysis and disciplines like it
qualify as .science. at all is a matter of increasing debate. In a sharply
critical report issued in 2009, the National Academy of Sciences said,
.The simple reality is that the interpretation of forensic evidence is not
always based on scientific studies.. Taking aim at disciplines as varied
as ballistics, hair and fiber analysis, bite-mark comparison.even
fingerprints.the report declared, .This is a serious problem..
The last few years have seemed to bear out the report. Dozens of elite
crime labs all over the country, from Nassau County, N.Y., to San
Francisco, to Virginia, Cleveland, Oklahoma, and Baltimore, have been
involved in scandals involving mishandled evidence and false or misleading
forensic testimony. This past summer, a North Carolina attorney general.s
audit discovered that the state.s Bureau of Investigation had withheld or
distorted evidence in more than 200 cases.
Even some of the best funded and most sophisticated crime-fighting
organizations are being taken to task for their use of forensic evidence.
This week, the New York Times reported that the Federal Buerau of
Investigation had .overstated the strenght of genetic analysis. during the
investigation of Bruce E. Ivins, who allegedly mailed anthrax to newsrooms
and Senate offices in the wake of the 9/11 attacks.
A year-long investigation by the independent journalism nonprofit
ProPublica revealed major problems in the nation.s coroner system:
pathologists not certified in pathology, physicians who flunk their board
exams, even coroners who are not physicians at all. .In nearly 1,600
counties across the country,. the investigation found, .elected or
appointed coroners who may have no qualifications beyond a high-school
degree have the final say on whether fatalities are homicides, suicides,
accidents or the result of natural or undetermined causes..
For his forthcoming book, Convicting the Innocent: Where Criminal
Prosecutions Go Wrong (Harvard University Press, April 2011), University
of Virginia law professor Brandon Garrett examined the trial transcripts
and other legal documents of the first 250 people to be exonerated by DNA
in this country. He discovered that in more than half these cases, trials
were tainted by .invalid, unreliable, concealed, or erroneous forensic
evidence.. The errors ranged from analysts making up statistics on the
fly, implying that their methods were more scientific than they actually
were, and exaggerating or distorting their findings to support the
Peter Neufeld, a lawyer in New York and cofounder of the Innocence
Project, which has helped to facilitate many of these exonerations, calls
it the .elastic expert: no matter what you see, I can distort it so that
it would be a match..
This .elasticity. is possible because the tests are largely subjective.
Just how much human judgment is required depends on the discipline: DNA
testing is mostly.though not entirely.done by machine, for instance,
whereas microscopic hair comparison is based solely on the analyst.s
opinion. Even fingerprints, which many of us regard as foolproof tools for
identifying culprits.think Dexter feeding a print into his computer and a
bad guy.s photo and driver.s license appearing on the screen.in fact rely
largely on human interpretation, and therefore are subject to human error.
One of the most famous examples of the danger of fingerprints was the case
of Oregon lawyer Brandon Mayfield, arrested in 2004 in the wake of the
Madrid train bombings. Working from a partial print that Spanish
authorities had found on a plastic bag of detonators, several top FBI
analysts declared Mayfield.s print a match. That is, until Spanish
authorities identified Ouhnane Daoud, now wanted for terrorism in
connection to the crime. When it became clear that Daoud.s prints were a
much better match, the FBI was forced to admit that its own bias and
.circular reasoning. had led them to Mayfield, who had no involvement in
Part of the problem is what social scientists call .context bias.. Most
forensics labs are located within police departments, so analysts may see
themselves as working .for. the prosecution. They also usually have
information about the evidence they.re testing.for example, that the
suspect has a prior record. .There.s a lot of research to suggest that
knowledge could have biasing effect,. says Jennifer Mnookin, a professor
at the UCLA School of Law.
In a recent Supreme Court case, Justice Antonin Scalia, writing for the
majority, said that whether consciously or not, an analyst .responding to
a request from a law enforcement official may feel pressure.or have an
incentive.to alter the evidence in a manner favorable to the prosecution..
The judges. ruling means that forensic test results may be subject to the
same kind of scrutiny as any other evidence, and an analyst from the lab
that ran the test must be present in court to be cross-examined, just like
any other witness.
.Obviously, most people in this community are trying to do their jobs well
and are not trying to frame innocent people,. says the University of
Virginia.s Garrett. .But what we.ve seen come out of these exoneration
cases and in additional scandals at the laboratories is that this is not a
problem of a few bad apples. Who is the competent analyst that can testify
about a technique that.s fundamentally unreliable? That.s not a bad-apple
problem. That.s a serious problem with our entire system..
At the heart of these criticisms is the issue of what scientists call
validity and reliability. A test is valid if its results are factually
accurate. A test is reliable if multiple tests will lead to the same
conclusion. Some forensics tests, like blood typing, are very reliable: no
matter how many times your doctor draws your blood, you will always have
the same blood type. Occasionally there are mistakes, of course, but they
are predictable: blood-typing tests have well-documented and
well-understood error rates. Others, like hair comparison, are unreliable:
studies have shown that multiple technicians examining the same two
hairs.even the same technician examining the same two hairs at different
times.come to multiple conclusions. Critics say that many of forensic
science.s most basic tools are neither reliable nor valid.
For example, at the trial of Jimmy Ray Bromgard, who served more than 14
years of a 40-year sentence for sexual intercourse without consent until
he was exonerated in 2002, the director of the Montana State Crime Lab
told the jury that hairs found on a blanket in the victim.s house
.matched. hairs taken from Bromgard.s body. There were so many hairs that
matched so well, the analyst said, that there was a .one in 10,000. chance
the hairs could have come from anyone else.
But no one has ever established any statistics about the microscopic
characteristics of hair, so .one in 10,000. odds isn.t based on scientific
consensus. How common is it for a person to have a particular hair color,
or for a hair to crinkle or curl just so? Scientists have never answered
that question systematically. And what does .match. mean, anyway? There
are no uniform guidelines to say how many characteristics two hairs must
have in common before they.re said to .match.. It varies entirely from one
lab to the next, from one technician to the next.
Barry Fisher, who served as the crime-laboratory director for the Los
Angeles Sheriff.s Department for more than 20 years, was often stymied by
this problem when he took the stand. .How do you convey the level of
certainty?. Fisher asks. .Do you say to the jury, .I.m pretty sure.? .I.m
very sure.? What do these things mean?.
To get around this problem, Garrett found, forensics experts too often
overreach in their testimony.
When Ray Krone was convicted of murder in Arizona and sentenced to death
in 1995, the testimony of a bite-mark analyst was key to the state.s case.
.This is really an excellent match,. the analyst said on the stand,
comparing Krone.s teeth with a bite mark on the murder victim. .That tooth
caused that injury..
In fact, in its report the National Academy of Sciences found that, among
all the forensic disciplines, only DNA has proved capable of
.individualization..that is, demonstrating .a connection between evidence
and a specific individual or source.. When the DNA in the Krone case was
tested year later, he was exonerated, but only after spending a decade in
The report has led a small but growing number of judges to take a more
skeptical approach to forensics. In addition to the Supreme Court case,
Melendez-Diaz v. Massachusetts, U.S. District Court Judge Nancy Gertner
announced in March that she will allow forensic evidence in her courtroom
only if a lawyer first proves in a pretrial hearing that the method is
scientifically sound. .In the past, the admissibility of this kind of
evidence was effectively presumed, largely because of . the fact that it
had been admitted for decades,. Judge Gertner wrote in her order. .The NAS
report suggests a different calculus..
The National Institute of Justice has funded some preliminary studies to
establish the scientific information that has so far been missing; UCLA.s
Mnookin and her colleagues are less than a year into a two-and-a-half-year
grant to develop a more formalized and scientifically validated approach
to fingerprint analysis. .It.s not that we know that they don.t work,.
Mnookin says of fingerprints and other forensic methods. .It.s that we
don.t have enough evidence about when they work, how they work, when they
might not work.. The report also led to a series of Senate Judiciary
Committee hearings. In January Senator Patrick Leahy (D-Vt. introduced a
bill to address some of the major issues in the nation.s forensic system.
The The Criminal Justice and Forensic Science Reform Act takes up many of
the issues identified in the NAS report. Although the report has gotten a
chilly reception from many forensics experts and prosecutors, many others
in the field, like Fisher, believe reforms in the system are long overdue.
Geoffrey Mearns, a former federal prosecutor who helped try both Oklahoma
City bombers Terry Nichols and Timothy McVeigh, regularly used forensics
in his work. Mearns served on the committee that wrote the academy.s
report. .I had assumed that there were well-established uniform processes
and procedures in place. I really had faith in the accuracy, reliability,
and that it was well grounded in science,. says Mearns, now provost and
senior vice president for academic affairs at Cleveland State University.
.When I realized my faith was not well placed, I was very concerned about
the damage that it was doing to the accuracy and efficiency of
law-enforcement investigations. Because if the science is not accurate,
and is leading us to the wrong person, it.s not only causing a terrible
injury to the wrong person, but it.s leading you away from the right
The 265 innocent people so far exonerated by DNA are lucky. Among the
.hundreds, if not thousands. of people that the Innocence Project.s Peter
Neufeld estimates were wrongfully convicted on the basis of faulty
forensics, only a small percentage have DNA available to test. What is
their recourse? Neufeld says his organization is counseling attorneys to
submit a writ of habeas corpus.the legal system.s document of last
resort.on the basis of newly discovered evidence: the fact that forensic
science is not as scientific as it purported to be at the time of trial.
However, .given the reluctance of judges to ever set aside convictions
with anything less than DNA,. says Neufeld, .I am not as optimistic as I
would like to be despite the fact that there.s a matter of fairness..
One of those exonerated after 15 years in prison was Roy Brown. He was
convicted of murder in 1992 and sentenced to 25 years to life, partly on
the basis of a bite-mark analyst who said that Brown.s teeth matched a
wound on the victim .to a reasonable degree of dental certainty.. The fact
that whoever had bitten the victim had six teeth on his upper jaw.the
wound clearly had six impressions.whereas Roy Brown had only four was
.inconsistent,. the analyst admitted, .but explainably so in my opinion..
DNA proved him innocent in 2006.
Beth Schwartzapfel is a Brooklyn freelance journalist with an interest in
criminal justice issues.
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