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- LAW, Page 63A Trial of High-Tech Detectives
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- DNA testing may not be so foolproof as once thought
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- A technique called DNA fingerprinting has, since the
- mid-1980s, become an important tool for police and prosecutors.
- Matching a suspect's DNA, the genetic material found in most
- cells, with DNA found in blood or semen at the scene of a crime
- can provide seemingly indisputable evidence of guilt. But now
- DNA fingerprinting is itself on trial, and shadows of doubt are
- falling on detective work that once seemed virtually infallible.
- Says William Thompson, a professor of social ecology at the
- University of California at Irvine: "This technology has been
- steamrollered through the courts, and now it's beginning to get
- serious scrutiny."
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- At the center of the controversy is a pretrial hearing that
- ended last week in the same Bronx, N.Y., courthouse that was
- depicted in Tom Wolfe's best seller The Bonfire of the
- Vanities. Joseph Castro, a 38-year-old janitor, stands accused
- of killing a neighbor and her two-year-old daughter. According
- to the prosecutors, a portion of DNA extracted from a spot of
- blood on Castro's watch matched DNA taken from the murdered
- mother. The chance of such a match occurring at random, said
- scientists called by the prosecution, was 1 in 100 million.
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- But the defense enlisted scientists of its own to review
- the evidence. A panel of experts from both sides eventually
- agreed that the evidence presented was "not scientifically
- reliable enough." They did not say the DNA analysis was invalid
- but asserted that in this case it was not nearly so precise as
- the prosecution claimed. One expert calculated that there was
- a 1 in 78 chance that the blood on Castro's watch was not from
- the victim. That may be a small chance, but to the defense it
- constituted a distinct shadow of a doubt.
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- The judge in the Castro case is expected to rule in June on
- the admissibility of the DNA test as evidence. His decision
- could have reverberations across the U.S., since evidence from
- DNA analysis has led to dozens of convictions and helped put at
- least two men on death row. Now many of these cases may have to
- be re-examined. Says Randolph Jonakait, a professor at New York
- Law School: "(The Castro case) is a bombshell in DNA
- litigation."
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- Advocates of DNA fingerprinting still maintain that the
- tests are practically foolproof if done properly. "It's not the
- technology that's being challenged," says John Hicks, a deputy
- assistant director of the FBI, "but the proficiency of the
- tester." Unlike traditional fingerprinting, which is done by
- police experts in official labs, DNA testing is carried out by
- several private firms that specialize in the technique, and the
- courts have no direct control over the quality of the work. The
- tests in the Castro case were performed in 1987 by the oldest
- and largest company in the business, Lifecodes of Valhalla, N.Y.
- The firm insists that it has refined its methods in the past two
- years.
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- Still, Lifecodes and other DNA-testing companies say they
- would welcome official standards for their laboratory
- procedures. Such standards are being developed by the FBI, along
- with several state governments. If this new industry is
- adequately regulated, then DNA fingerprinters could once again
- become reliable witnesses instead of suspects.
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