A new type of DNA evidence will be used for the first time in a Maryland courtroom next week when prosecutors introduce a microscopic speck of saliva in the trial of a man accused of killing a 55-year-old Arnold woman.
Judge Raymond G. Thieme Jr., of Anne Arundel County Circuit Court, ruled yesterday that the evidence, derived from a test known as Polymerase Chain Reaction (PCR), could be used against Albert Gustav Givens, an Annapolis handyman.
Mr. Givens, 38, of the 100 block of Roselawn Road was charged with first-degree murder and first-degree sexual assault seven months after Marlene "Pat" Kilpatrick was found fatally stabbed in her home in the 100 block of Church Road.
It was the PCR test performed on saliva taken from a soda bottle found in the kitchen of Mrs. Kilpatrick's house that led police to Mr. Givens, who had painted the house and done yard work.
The trial is scheduled to begin next Wednesday.
Judge Thieme decided to allow the PCR results after a hearing in which molecular biologists for both sides argued about its reliability.
Dr. Charlotte Word, of Cellmark Diagnostics in Germantown, explained that PCR testing amplifies a tiny sample of DNA that is either too fragmented or too degenerated or damaged to be tested under the traditional process, known as Restriction Fragment Length Polymorphism (RFLP).
The results of those tests have been admissible in Maryland since 1990.
Dr. Word, testifying for the prosecution, said that the PCR testing process can accurately link a suspect to a tiny body fluid sample found at a crime scene.
It has been used by the FBI and prosecutors in several states and endorsed by the California Association of Crime Lab Directors, Dr. Word said.
"It's basically revolutionized molecular biology," she said.
But Dr. Jay Doniger, a defense biologist from Georgetown University, said that PCR is too unreliable for criminal trials because no matter how careful the analyst and the lab, there always is a chance for error.
Dr. Doniger said it is too easy for such microscopic samples to become contaminated.
"It's very, very difficult to avoid contamination [of the sample inPCR] and the reason is that the test is so damn sensitive," he said.
Kathleen S. Rogers, assistant state's attorney, said she requested the hearing to ensure the PCR test results could be used.
William Vossberg, a forensic chemist for the Anne Arundel County Police Department, said PCR has been used by police departments in at least 30 other states.
Mrs. Kilpatrick's body was found by her daughter in a rear bedroom on the morning of Jan. 2, 1992, with a knife embedded in her chest.
Police said Mr. Givens, who had worked for Mrs. Kilpatrick, became a suspect early in the investigation because there were no signs of forced entry to the house, leading them to suspect she knew her killer.
They also said Mr. Givens allegedly implicated himself by making statements about the sexual assault that investigators said only the assailant could have known at the time.
Mrs. Kilpatrick, 55, retired from the Anne Arundel County Board of Realtors in 1985 after she was diagnosed with multiple sclerosis.
Despite her illness, Mrs. Kilpatrick was described as an activist determined to fight the debilitating effects of the ailment.
She was active in soup kitchens, Anne Arundel County public libraries and driving for the disabled.