Prosecutors and attorneys for Scotland E. Williams sparred in Anne Arundel Circuit Court yesterday over the reliability of microscopic evidence taken from the home of two lawyers shot to death in their house outside Annapolis last spring.
Mr. Williams is charged with two counts of first-degree murder in the deaths of Jose E. Trias, 49, and his wife, Julie Noel Gilbert, 48, who were killed in their weekend home May 16, 1994, at Winchester on the Severn.
Mr. Williams, 31, of the 800 block of Bradford Ave., Arnold, was arrested May 19 after a police detective identified him in video pictures taken at two Glen Burnie banks that showed the suspect using Mr. Trias' automated teller machine card.
In a pretrial hearing yesterday, Judge Eugene M. Lerner heard arguments from attorneys over whether a scraping of DNA from a drinking glass in the victims' home was reliable enough to be admitted into evidence at next week's trial.
Prosecutors say the DNA matches that of Mr. Williams.
Testimony focused on a type of DNA testing called Polymerase Chain Reaction, or PCR type DNA.
Before it may be used in a trial, a hearing on PCR's validity is required, if the defense requests it.
Charlotte J. Word, a molecular biologist for Cellmark Diagnostic Laboratories of Germantown, told Judge Lerner yesterday that the PCR type testing is "absolutely" reliable enough to be used.
It has been accepted in courtrooms and by molecular biologists nationwide and is being used by prosecutors in the O. J. Simpson murder case, she said.
Cellmark also is being used in that case, Ms. Word said.
"We've had no indications that we've ever had any systematic problem in the laboratory with it," she said.
But Mr. Williams' attorneys argued yesterday that the PCR, which is amplified in a laboratory before it can be matched to a suspect, is much less reliable than the Restriction Fragment Length Polymorphism (RFLP) DNA that has been used by police in criminal cases for several years.
Dr. John Gerdes, a molecular biologist from Denver, testified that such DNA test samples are so small that they may give inaccurate results if they become contaminated inadvertently by being touched by police or witnesses at crime scenes.
"It's really a very scary situation to me," he said.
The RFLP test has been admissible in Maryland courts since 1990. The PCR test was admitted for the first time in Maryland as evidence in another Anne Arundel County case.
Albert Gustav Givens, a handyman, was convicted and sentenced to life in prison last July for sexually assaulting and killing an Arnold woman in her home.
A key piece of evidence was a microscopic speck of saliva taken from a soft drink bottle found at the murder scene and linked to Givens through the PCR test.
Judge Lerner is expected to rule tomorrow or Thursday on whether to admit the DNA.
Jury selection is expected to begin Friday.