Unlocking the Cells.

• Author: Bailey, Ronald
• Position: Postconviction DNA testing of prisoners

DNA technology frees the innocent as well as convicting the guilty.

The impeachment of President Clinton underscored the growing importance of DNA evidence in criminal investigations. If it weren't for the telltale stain on a certain blue dress, the president might still be insisting that he "never had sexual relations with that woman, Ms. Lewinsky."

DNA testing was first used in Britain in 1986 to prosecute serial rapist and murderer Colin Pitchfork. Today, DNA testing is regularly used to convict criminals, much as fingerprints have been for many years. "No other form of evidence for identifying human beings has gone through such a rigorous scientific and legal validation as DNA has," says Christopher Asplen, executive director of the National Commission on the Future of DNA Evidence, a panel of expert advisers set up by the U.S. Department of Justice. "Now it's the most reliable evidence we've got."

DNA testing is a powerful way to identify people because nearly every human cell contains it, and each person's DNA is unique (except in the case of identical twins). In 1998, the Federal Bureau of Investigation created the National DNA Index System (NDIS), which links the DNA databases of 18 states so far. Eventually, all 50 states are expected to participate in the NDIS. These databases currently contain the genetic profiles of some 210,000 criminals and are expanding rapidly.

The profiles are based on DNA samples collected from people who have been convicted of murder, manslaughter, rape, or aggravated assault. Some states, such as Virginia, require that all convicted felons provide DNA samples for profiling. The databases are far from complete. Paul Ferrara, director of the Virginia Division of Forensic Science, estimates that the DNA of 1 million felons nationally should have been collected but has not been and that half a million samples that have been collected are still not profiled.

Despite these shortcomings, the databases have dramatically proven their value, solving scores of old murder and rape cases by matching DNA evidence from those crimes to DNA profiles. Florida claims to have made some 200 "cold hits" using the databases, and Virginia reports 78. A "cold hit" occurs when police who have no leads find a suspect by checking the DNA from a crime scene against the DNA profiles in the databases. Great Britain was an early innovator in DNA profiling, and British police claim to solve 300 to 400 crimes per week using DNA...