A link between DNA from the unsolved killing of Sarah Fox, a Juilliard
student, in 2004 and DNA taken from a chain placed at the site of an Occupy Wall Street action in March may be the result of a laboratory error, according to two people briefed on the investigation.
One of the people, who spoke on the condition of anonymity, said it
appeared that the DNA recovered from skin cells on the slain woman’s
portable compact disc player and from the chain found this year came
from a Police Department employee who works with the Office of the Chief
Nonetheless, the renewed focus on a DNA link to the Fox case has drawn
attention to the way investigators are now using DNA collection for far
more than just the most serious of crimes.
The decision by investigators to search for DNA samples on the chain,
which was used to hold open a subway entrance gate, illustrates how such
collections have become a routine part of a wide range of criminal
The expansion of DNA collection at crime scenes in New York accelerated
around 2007, when the medical examiner’s office opened a new DNA
laboratory on East 26th Street and First Avenue and began building a
larger staff, greatly expanding the number of samples it could analyze.
It also reflects advances over the years in the ability of investigators
to extract DNA from skin cells left behind on surfaces like doorknobs,
said Mechthild Prinz, the director of the department of forensic biology
in the medical examiner’s office.
The ability to analyze such samples, which are known as “touch DNA,” has
allowed investigators to use DNA from scenes where bodily fluids may be
absent, Dr. Prinz said. Investigators said that the more heavily the
suspect was sweating, the more likely he or she was to leave a useful
touch DNA sample.
In 2011, the city medical examiner’s office issued some 11,000 reports
involving DNA collected from crime scenes, compared with about 3,000 in
2006, Dr. Prinz said. Reports generally correspond to a single incident,
and may involve multiple samples.
Last year, about 32 percent of the incidents in which DNA was sought
were property crimes, primarily burglaries and robberies, Dr. Prinz
said. Homicides make up only 6 percent of the incidents from which DNA
is sought, and sexual assaults are an additional 20 percent. Recovered
weapons are swabbed for DNA, too, and account for about 10 percent of
the caseload. The remaining cases, Dr. Prinz said, involved DNA taken
directly from known suspects for comparison, as well as an assortment of
missing person cases, hate crimes, arsons, and other crimes.
In 2011, the medical examiner’s office entered DNA profiles taken from
about 2,050 criminal events that year into the F.B.I.’s DNA database.
About 24 percent of those resulted in a match against the DNA profiles
of known individuals, she said.
At present, the Police Department’s evidence collection units focus DNA
collection on crimes for which the police have no suspect. Because those
who commit robberies and burglaries are usually strangers to their
victims, DNA is a particularly useful tool with those types of crimes,
Dr. Prinz said. For that reason it is unlikely that DNA will soon become
a routine part of drug possession cases, where the suspect is already
identified by the police.
“We want to focus on the cases where identity needs to be established,” Dr. Prinz said.
Dr. Prinz declined to comment on the Fox case. But an official with
knowledge of the matter said that the medical examiner’s office had run
the DNA found on the compact disc player and the chain through the
office’s employee DNA database more than once.
Ellen S. Borakove, a spokeswoman for the medical examiner’s office,
said, “We’ve excluded all medical examiner’s office personnel.” She
added, “We are still actively investigating the match.”
One person familiar with the investigation said that the DNA came from a
supervisor in the Police Department’s laboratory, which is also
involved in such testing.
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