By PAMELA GOULD

For Bill Thomas, the past year has been like a roller-coaster ride and he's still reeling from the latest gut-busting plunge.

Last fall, his family and seven others who lost loved ones in what are known as the Colonial Parkway murders were stunned to learn that graphic photos from the four crime scenes in the Tidewater area had become public.

After expressing their horror, the families were encouraged when the FBI agreed to assign an agent full time to the two cases--and four killings--it had been tasked since the 1980s with solving.

The Virginia State Police, lead agency in the other two Colonial Parkway cases, did not follow suit.

Still, the families were heartened that the FBI would look for similarities to other slayings, including several unsolved cases across Virginia, such as the May 1996 deaths of Julie Williams and Lollie Winans in Shenandoah National Park.

And the families of the victims were hopeful when the FBI also agreed to submit evidence from its cases to the FBI lab at Quantico to see if applying new science could help find a killer, or killers.

Both of those moves provided the first glimmer of hope the families of Cathleen Thomas, Rebecca Dowski, Keith Call and Cassandra Hailey had felt in more than two decades.

But this summer, those families got discouraging news.

And when the 24-year anniversary of Bill Thomas' sister's death arrived this month, he was crestfallen.

DISCOURAGING RESULTS, PENDING DEPARTURE

This summer, the FBI failed to find useful forensic evidence among the items from the apparent slayings of Call and Hailey, who disappeared in April 1988 but whose bodies haven't been found, Thomas said.

And last month, Thomas' family got bad news as well.

Forensic tests on key pieces of evidence from his sister's October 1986 slaying had so far failed to produce a DNA profile, Thomas said. He also expressed concern that he could not get a written report summarizing the findings.

But he's holding out hope that testing on other evidence will prove fruitful.

A.J. Turner, supervisor of the FBI's Norfolk office, declined to comment on the lab results. He said, in response to a list of questions, that exams are ongoing but it's "difficult to predict" when they'll be finished.