When science comes to the courtroom in two pending rape trials here, the outcome may hinge not so much on police detectives as on DNA detectives. The trials, including one involving a former Juvenile Court officer, will be the first in West Tennessee to use so-called DNA fingerprinting. The controversial process of using genetic material to link suspects to crimes has been used several hundred times since it was first used in 1987 to convict an accused rapist in Florida. it has been used in solving paternity cases since the 1970's.
Criminal investigators say the cellular testing method is the greatest breakthrough since fingerprint identification was developed in the early 1900's. Although not yet as precise as comparing fingerprints, they say DNA testing can identify someone often with a 1-in-a-100-million chance of error or less.
But critics say the probability numbers are exaggerated and that often the chance of error may be as great as 1 in 128. They worry that jurors may be blinded by science and the result could be the conviction of innocent defendants. "It's far too young to be relied upon as heavily as it is," defense attorney Mark McDaniel said. "In the early 1900's they built a boat (the Titanic) that was supposed to be unsinkable. How many people lost their lives on the unsinkable boat?"
In any event, DNA in the courtroom appears here to stay. Although several trial judges have banned it as unreliable, most judges believe DNA fingerprinting has gained general acceptance in the scientific community and are allowing DNA in the courtroom. Last year the Tennessee legislature passed a bill allowing DNA evidence into courtrooms and directing Tennessee Bureau of Investigation to establish a DNA testing lab and a DNA data bank of convicted sex offenders to identify or eliminate suspects in future crimes.
"Three years ago it was met with disbelief but juries usually understand what's going on now," said mark Stolorow of Cellmark Diagnostics, a private DNA testing lab in Germantown, MD, near Washington. "The next step is to make testing faster, more sensitive, and to improve the precision." But that may take another five years and critics point out that current testing is done on only the parts of the genetic material that are most likely to differ from person to person. Thus, critics say, this leads to inflated claims of accuracy...
DNA results will play an important role in the pending trial of a former Juvenile Court probation officer, William T. Wilson, 24, accused of raping two teenage girls in detention in July 1989. Since the alleged incident occurred before the legislature authorized courts to include DNA evidence in trials, the decision was left to Criminal Court Judge W. Fred Axley during a hearing last week. His courtroom looked more like a science classroom, complete with overhead projector, lecturers with pointers and slides illustration some fine points of biochemistry, genetics, and molecular biology. But no one was dozing. Instead, nearly a dozen defense lawyers and prosecutors watched from the audience and got a sneak preview from an FBI expert of what will likely become a common trial tool. "I think we will get to the point one day where DNA will replace fingerprints," prosecutor Chris Craft said, "It's science now but I think it will eventually become commonplace."
Critics say two key problems with current DNA testing are that no outside agency has been allowed to examine the FBI's lab methods for quality control and that the population data base it uses for comparisons is too broad and thus results in inflated accuracy rates. Some scientists have even accused the bureau of trying to stifle criticism by pressuring scholarly journals to shape their articles toward the FBI's liking. "There's big turmoil in the scientific community," said attorney McDaniel. "it's beginning to receive some vigorous challenge."
Still, DNA's courtroom proponents are relying on studies such as one published earlier this year by two Yale University scientists. The study said in part that an innocent suspect could be wrongly convicted by DNA fingerprints "only in you have an evil twin."