When Roanoke police sent samples taken from the Cynthia McCray and Audrey West homicide cases to the state forensic lab more than 20 years ago, scientists could do little more than identify blood types and keep evidence for comparison if investigators ever found a suspect.

When a cold case investigator resubmitted that same evidence within the past 18 months, scientists reported startling results matching a profile from the state DNA database -- the same man in both cases, William Ray Hagy Jr.

The DNA hits led Roanoke prosecutors to seek murder indictments against Hagy in both cases Monday. Yet while advances in forensic technology have led to a potential resolution for both unsolved homicides, "the work has really just begun in these cases," said Roanoke police Capt. Chris Perkins.

The biggest challenges ahead involve finding the investigators and witnesses who would have been available had the cases gone to trial in the mid-1980s.

Though DNA can make for powerful evidence, "there hopefully will be additional evidence to supplement the DNA," said Roanoke Commonwealth's Attorney Donald Caldwell.

The prosecutor declined to discuss what the other evidence might be. "Mr. Hagy is presumed innocent, and we'll see how it goes at trial."

Monday's grand jury indicted Hagy, 48, on murder and rape charges in the death of West in 1985 and murder in McCray's 1984 killing. The grand jury also indicted Hagy on charges of rape and abduction with intent to defile and rape in a 1984 assault on a woman who was 17. That woman now lives in Oregon, Caldwell said. There has not yet been any indication from authorities that her case is tied to DNA evidence.

Hagy already is serving a 50-year prison sentence after a jury found him guilty in 1985 of raping and sodomizing a 14-year-old girl. He maintained his innocence at the time and later attempted to appeal the verdict.

Roanoke authorities believe that the two rapes and the two homicides all happened within a seven-month period from October 1984 to May 1985.

Though police believe they have accounted for all the crimes in Roanoke in which Hagy is considered a suspect, his DNA profile has been entered into a national FBI database. "We know he did some traveling during those years," Perkins said.

McCray's partly clothed body was discovered Nov. 28, 1984, by railroad tracks underneath the Interstate 581 bridge over Campbell Avenue.

On May 17, 1985, West's nude body was discovered in her home on Walnut Avenue Southwest by her ex-husband.

Both women had been strangled.

Roanoke Detective L.P. Manning, who is in charge of re-examining cold cases, reviewed the evidence in McCray's death in early 2007 and decided to reopen the case. The reopening of West's case was prompted by calls from her family, Perkins said.

According to court documents, Manning submitted McCray's clothes to the lab in February 2007. Three months later, a scientist reported that semen taken from her body and her underwear had a profile consistent with Hagy.

In January, Manning sent evidence from the West case to the lab, including a sheet, a jacket and DNA taken from her body. Semen tested in all three samples was linked to Hagy.

Manning also included blood samples from four men whom police had previously scrutinized as suspects in the West case. All four were eliminated by the tests.

The Department of Forensic Science has been retesting DNA from many cold cases because today's improved technology yields better results than past tests did, said Brad Jenkins, the department's DNA section chief.

The newer tests can be done with a smaller sample. In the past, a stain the size of a quarter was needed to test DNA. Now, lab technicians need a stain the size of a pencil lead, Jenkins said.

Properly stored DNA evidence does not deteriorate significantly over time, he said.

Jenkins declined to talk about any details of the cases involving Hagy.

The general public, and even lawyers and judges, tend to think of DNA evidence as infallible, said Steven Benjamin, a prominent Richmond defense attorney. But DNA matches aren't necessarily irrefutable proof.

"You have to question every aspect of that evidence," Benjamin said, including whether the evidence could be contaminated -- a risk that has grown as testable samples have become smaller.

Also, bias might cause the person conducting the test to claim a suspect can't be eliminated as a match from a DNA mix even if they can be, Benjamin said.

He added that cold DNA hits pose a problem for defendants because often so much time has passed that the person no longer remembers where they were specifically on the date in question, making an alibi impossible, even if the person is truly innocent.

"I anticipate that the DNA results in this will be scrutinized very closely," Caldwell said.

Staff writer Amanda Codispoti contributed to this report.