1:00 AM

By Ann S. Kim akim@mainetoday.com Staff Writer

PORTLAND -- Expert witnesses who testified Thursday in Dennis Dechaine's hearing on a new trial offered contrasting views on whether the DNA evidence at issue is a result of contamination.

Three DNA experts, with doctorates in genetics and extensive backgrounds in forensic science, testified about the partial DNA profile that is at the center of the multi-day hearing. Dechaine's lawyer, Steve Peterson, is trying to convince a judge that the jurors would not have convicted Dechaine of the 1988 murder and kidnapping of 12-year-old Sarah Cherry had they known about the DNA from an unknown male on the girl's left thumbnail.

Two witnesses for the state testified that the autopsy conditions described to them posed a high risk for DNA contamination. At the time, DNA technology was new and lacked the kinds of safeguards that are used today.

In 1988, the State Medical Examiner's Office did autopsies in the morgue of the Kennebec Valley Medical Center in Augusta. Earlier testimony indicated that instruments were kept in a metal tool box with towel-lined drawers. Instruments were sometimes rinsed and sometimes simply put back into the drawers. The towels got soiled with blood over time and were changed after several months.

"That scenario that you described would really be a textbook recipe for the potential for contamination for many, many steps along the way," Frederick Bieber said after the conditions were recounted by Deputy Attorney General William Stokes.

Bieber, who holds positions at Harvard Medical School and Brigham and Women's Hospital, said he has been at autopsies done under similar conditions, and dozens of people would handle instruments.

It probably wasn't until the early 1990s that precautions to prevent DNA cross-contamination became widespread in autopsy rooms, he said. Before then, it was common for autopsies to be done with bare hands. The first precautions were not related to DNA, but to guard against the transmission of infections like HIV or to protect cells that would be cultured.

Carll Ladd, supervisor of the DNA section of Connecticut's forensic lab, agreed that the conditions at the time of Sarah Cherry's autopsy would have been "ideal" for contamination.

See original here:
DNA focus for Dechaine trial