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- LAW, Page 63A Trial of High-Tech DetectivesDNA 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."
-
- 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.
-
- 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.
-
- 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.