After nearly four decades of unanswered questions, federal investigators announced they have finally identified the killer behind one of Virginia’s most haunting cold cases. 

The FBI Norfolk Field Office announced Tuesday that advances in forensic science have linked the 1986 murders of Cathleen Thomas and Rebecca Dowski, victims of the infamous Colonial Parkway murders, to a deceased suspect allegedly responsible for at least six killings.

FBI investigators determined Alan Wade Wilmer Sr. murdered the two women last seen together Oct. 9, 1986, at a computer lab at the College of William and Mary in Williamsburg.

Wilmer Sr., a local fisherman who died in 2017 at the age of 63, was connected to a series of at least six murders and disappearances of young people in Virginia between 1986 and 1989, according to the FBI.

He lived in Lancaster County and spent most of his time fishing and hunting, often docked at marinas in Gloucester and Middlesex counties.

Between 1986 and 1989, a series of violent crimes took place near Virginia’s Colonial Parkway and surrounding areas, resulting in the murders and disappearances of at least eight young people, according to officials. 

The crimes were known as the Colonial Parkway murders, one of the longest cold case investigations in Virginia history.

After the disappearance of Thomas, 27, and Dowski, 21, their bodies were found inside their vehicle along the Colonial Parkway, stabbed and strangled. It is unclear if the women were sexually assaulted.

Though the case remained unsolved, advances in forensic science and DNA analysis recently led to Wilmer's identification as the suspect allegedly responsible for the women's killings.

The U.S. Attorney’s Office for the Eastern District of Virginia said that, had Wilmer been alive, evidence would have supported federal prosecution.

Authorities said Wilmer was also responsible for the 1987 murders of David Knobling, 20, and Robin M. Edwards, 14, in the Isle of Wight and the 1989 homicide of Teresa Lynn Spaw Howell, 29, in Hampton, Virginia.

The bodies of Knobling and Edwards, who were last seen together on Sept. 19, 1987, were found dead days later with gunshot wounds along the shoreline of the Ragged Island Wildlife Management and Refuge Area on the south bank of the James River. Edwards, who was just 14 years old, was sexually assaulted, according to officials.

Two years later, on July 1, 1989, Howell was found dead in a wooded area after leaving a nearby nightclub.

FBI Norfolk said Thomas was a "vibrant young woman" known for her compassion, intelligence and close relationships with family and friends. 

They added Dowski was a talented musician and college student with a "promising future" and is remembered for her creativity, kindness and love of music.

"I am incredibly proud of the work done by the men and women of FBI Norfolk, whose tenacity and commitment to justice never wavered," Dominique Evans, special agent in charge of the FBI Norfolk Field Office, wrote in a statement. 

"This investigation demonstrates the strength of our partnership with the Virginia State Police, the Hampton Police Division and the Suffolk Police Department and our shared determination to never give up on victims or their families," Evans added. "We are thankful that advances in technology and DNA evidence allowed us to finally bring answers in this case." 

The Hampton Police Division thanked the community for its continued support and valuable information.

"It is our hope that this development provides the families with a measure of closure, comfort and peace," the division wrote in a statement. The women's families attended the announcement of closure of the case, though Thomas' brother, Bill, told local outlet 13 News Now he believes there were more than eight victims in the Colonial Parkway murders.

"I personally think that Alan Wade Wilmer Sr. is good for additional murders as well," Thomas told the outlet. "Right now, the way the laws are set up, even though Alan Wade Wilmer Sr. is a serial killer and has killed at least six people, including my sister, and her girlfriend Rebecca Dowski, we do not have the capability to upload his DNA into CODIS, because he was never convicted of a crime before he died in 2017."

The families are working to amend current laws to bring other unsolved cases to a close.

FBI Norfolk said investigators will continue to actively pursue unsolved cases related to the Colonial Parkway murders.

Fox News Digital's Chris Eberhart contributed to this report.