Examiners had long testified in court that they could
determine what fingertip left a print, what gun fired a bullet, which scalp
grew a hair “to the exclusion of all others.” Research and exonerations by DNA
analysis have repeatedly disproved these claims, and the U.S. Department of
Justice no longer allows technicians and scientists from the FBI and other
agencies to make such unequivocal statements, according to new
testimony guidelines released last year.
Though image examiners rely on similarly flawed methods,
they have continued to testify to and defend their exactitude, according to a
review of court records and examiners’ written reports and published articles.
ProPublica asked leading statisticians and forensic science
experts to review methods image examiners have detailed in court transcripts,
published articles and presentations. The experts identified numerous instances
of examiners overstating the techniques’ scientific precision and said some of
their assertions defy logic.
The FBI declined repeated requests for interviews with
members of the image group, which is formally known as the Forensic Audio,
Video and Image Analysis Unit.
ProPublica provided the bureau written questions in September
and followed up in November with a summary of our reporting on the bureau’s
photo comparison practices. The FBI provided a brief prepared response last
month that said the image unit’s techniques differ from those discredited in
recent studies. It said image examiners have never relied on those methods
“because they have been demonstrated to be unreliable.”
But the unit’s articles and presentations on photo
comparison show its practices mirror those used in the studies.
The bureau did not address examiners’ inaccurate testimony
and other questionable practices.
Judge Jed Rakoff of the United States District Court in
Manhattan, a former member of the National Commission on Forensic Science, said
the weakest pattern analysis fields rely more on examiner intuition than
science. Their conclusions are, basically, “my hunch is that X is a match for
Y,” he said. “Only they don’t say hunch.”
Rakoff said that image analysis hadn’t come before him in
court and wasn’t taken up by the commission but said that investigators,
prosecutors and judges should make sure evidence is reliable before using it.
Scandals involving other areas of forensic science have
shown the danger of waiting for injustices to become public to compel reform,
Rakoff said.
“How many cases of innocent people being wrongly convicted
have to occur before people realize that there’s a very broad spectrum of
forensic science?” Rakoff asked. “Some of it is very good, like DNA. Some of it
is pretty good, like fingerprinting. And some of it is not good at all.”
Details on FBI caseloads and testimony are not readily
available to the public. As such, there is no way to determine exactly how
often image examiners testify and when their photo comparisons serve as central
evidence in prosecutions. In court, examiners have said they analyze photos in
hundreds of cases a year, according to trial transcripts.
To try to identify some of those cases, ProPublica searched
court databases and found more than two dozen criminal cases since 2000 in
which documents mentioned the FBI’s image examiners, nearly all cases that were
appealed and thus had a substantial written record. Few criminal convictions,
though, make it to an appeal.
None of the appealed cases led to judges reversing
convictions, nor has evidence emerged to show that the defendants were
innocent. Still, flaws in forensic science techniques often emerge decades
after they’ve been allowed by judges and been used to secure convictions.
The problems with the FBI’s photo comparison work plague
other subjective types of forensic science, such as fingerprint analysis,
microscopic hair fiber examination and handwriting analysis, said Itiel Dror, a neuroscientist who
trains U.S. law enforcement on cognitive bias in crime laboratories. Dror is a
researcher at University College London, frequently teaching at agencies like
the FBI and New York Police Department on ways to minimize personal beliefs from
influencing casework.
Even DNA analysis can be swayed
by bias, Dror said. But pattern-matching fields like image analysis are
especially vulnerable. Image examiners’ lab work is, generally, only seeing if
evidence from a suspect “matches” that from a crime scene.
“Many of them are more concerned by what the court accepts
as science rather than being motivated by science itself,” Dror said.
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