'Touch' DNA offers hope in cold investigations

— -- For 35 years, Anne Arundel County, Md., police have been baffled by the murder of a 17-year-old girl whose battered body was discovered in an abandoned quarry near the suburban Washington city of Bowie.

Last month, David Cordle, chief investigator for the county's State Attorney's Office, attended what would have been Donna Dustin's 35th high school reunion in pursuit of information about her death. His visit produced 18 leads, two new names — but no definite answers.

Cordle has not given up hope. The investigator has submitted evidence for new forensic testing using a DNA technique that in July cleared JonBenet Ramsey's family in her death.

The success of the little-known method in her case is triggering requests for the test from law enforcement officials seeking similar breakthroughs in unsolved crimes. Private and state-run laboratories report increases of up to 20% in use of the technique called "touch" DNA.

Analysts scrape or swab surfaces such as clothing or food to try to get enough microscopic cells to identify or rule out suspects in violent crimes, robberies and burglaries. Unlike other DNA methods, touch DNA is used on surfaces without a visible stain, such as blood, but that investigators suspect might contain genetic material.

Experts say the technique can provide a powerful tool to develop fresh leads in unsolved cases, some of which are decades old.

"In select cases, this has the potential to find a person's DNA when it couldn't be found before," says Gregory J. Davis, professor of pathology and laboratory medicine at the University of Kentucky College of Medicine. "It has great potential for prosecutors who may be able to confirm a suspect's location at the time of the crime and for defense attorneys who may argue that their client was nowhere near the scene of the crime."

Cordle, past president of the Mid-Atlantic Cold Case Homicide Investigators Association, said he decided to seek the "touch" DNA testing after he attended the association's conference last month in Annapolis, Md., which featured the analyst who oversaw the method's use in the Ramsey case. "Some people think it's a shot in the dark," he says. "But if you don't have anything else, why not go for it?"