Tuesday, October 13, 2009

Amazing DNA Hits

Susannah Chase

In The Blooding, author Joseph Wambaugh describes the 1987 case of serial murderer Colin Pitchfork. After the rapes and murders of two 15-year-old schoolgirls, Lynda Mann and Dawn Ashworth, police in Leicestershire, England had no leads. They were certain the killer was local, but could find no clues as to his identity. When investigators learned that a local scientist named Alec Jeffreys had developed a method of “fingerprinting” blood, they contacted the mad scientist and he agreed to help them.

After years of intense investigation, police arrested a dim-witted 17-year-old kitchen porter named Richard Buckland. The evidence against him, however, was so weak that detectives decided to ask Jeffreys to use the new science to cement the case. Fortunately for Buckland, his DNA profile did not match the profile Jeffreys had developed from semen collected at the scene of the crimes. Police released Buckland, then took the desperate steps of collecting blood from all 17 to 35-year-old males in the area. Investigators eventually “blooded” 4,500 men and identified the aptly-named Pitchfork as the killer.

So began one of the most amazing breakthroughs in criminal history.

After just two decades, DNA has helped identify thousands of rapists and murderers. In addition, hundreds of accused killers have been exonerated by the same techniques. There is now a national databank of DNA profiles collected from convicted felons. Most states also have databases. Many state and local police departments currently have cold case units that focus on old unsolved cases. DNA gathered from victims and crime scenes by former investigators have contributed to solving many of those cold cases.

For instance, the Georgia Bureau of Investigation has solved more than 1,500 cases, some dating as far back as eighteen years.

On Halloween night, in 2007, a 68-year-old woman was murdered in Jonesboro, Georgia. Geneva Strickland was tied up, beaten, robbed, and her house set afire. Criminalists were able to gather foreign DNA from the scene. Running it through their database, they identified Timothy Alan Booth as the perpetrator. Booth had been in and out of prison for years, and had been forced to submit his saliva for a DNA profile while incarcerated. “I doubt the case would have been solved without DNA,” Jack Ivey said. “They talked to everybody in the family and had no idea who did this to mom.”

Eleven years after University of Colorado student Susannah Chase was abducted, raped, and murdered, DNA tests proved that Diego Olmos-Alcade was responsible for her death. Before murdering Chase, he had been sentenced to 10 years for another kidnapping. While in prison, he was required to give a sample of his DNA. Olmos-Alcade was not even on the radar as a suspect before the DNA hit.

Scientific advances in DNA technology have allowed investigators to test smaller and smaller traces of blood, saliva, or even skin cells. In 1984, Bradley Perry worked the graveyard shift at the Texaco Short Stop convenience store in Brigham City, Utah. At about 4:00 a.m., he was murdered and the store robbed. Police found a dollar bill at the scene and were surprised to discover minute traces of blood on it. In 2005, a lab was able to swab enough blood from the bill to get a DNA profile. Glenn Howard Griffin, a career criminal, was convicted and sentenced to life in prison for Perry’s murder.

DNA also has a history of clearing the innocent. After a woman in a Dallas, Texas suburb was raped, she picked Charles Chatman out of a lineup. Based only on that identification, the 20-year-old was arrested. Convicted of aggravated sexual assault, he was sentenced to life in prison. Twenty-seven years later, a vaginal swab taken from the victim was tested. It didn’t match the DNA profile of Chatman and he was released. More than half his life had been spent behind bars.

Polygraphs can fail. Eyewitnesses are fallible. Cops can make mistakes or worse, frame the innocent. But a science developed only two decades ago is proving to be as reliable as fingerprints.

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