Authorities ID Alleged Killer of Karen Klaas, the Ex-Wife of Righteous Brothers Singer

The mother was killed 41 years ago in her Hermosa Beach, California, home.

— -- Forty-one years after the brutal murder of Karen Klaas, a mother of two and ex-wife of Righteous Brothers' singer Bill Medley, authorities in California announced today that they've identified her alleged killer.

Klaas, 32, had returned home from dropping her son off at school Jan. 30, 1976, when she was attacked at her Hermosa Beach home.

Police said she was found by friends, who went to her house after she failed to meet them for coffee. Klaas has been sexually assaulted, strangled and left unconscious. She was hospitalized in a coma but died five days later on Feb. 4, 1976.

During a news conference today, authorities with the Los Angeles County Sheriff's Department identified her alleged killer as Kenneth Eugene Troyer. They said Troyer was 29 at the time of crime.

Police said that in 2016, they were able to link Troyer to biological evidence found at the crime scene using "familial DNA." With familial searching, a crime scene DNA profile is run through a state data bank to see if links can be found to similar profiles belonging to a relative.

"Familial DNA search is the only reason Troyer was identified in this horrific crime," Los Angeles County Sheriff Jim McDonnell said today.

Familial DNA search is legal in 10 states but the method is controversial. Civil liberties supporters have argued that the tactic has led to false leads and an invasion of privacy.

“Family members of the potential suspect are now subject to questioning that certainly is not fair,” Robin Sax, a criminal law expert, told ABC News.

In January 1982, Troyer was serving a prison sentence for burglary in San Luis Obispo, according to a police news release, when he escaped.

"While on the run, he was identified as a suspect in other robberies, assaults and rapes in Orange County," a police news release said.

A task force was formed to find him, and he was fatally shot in March 1982 by police as they sought to arrest him. Because DNA collection of what McDonnell called "qualifying criminal offenders" was not allowed at the time, Troyer's DNA was not present in a state database run by the Department of Justice.

Police said that in 1999, a DNA profile from the biological evidence was obtained due to technology advances. In 2011, a familial search was conducted but no match was found. Five years later, in 2016, another familial search was requested and a match was located.

“It took a long time for this type of technology and science to catch up with the sample that had been collected a long time ago,” Elissa Mayo, a DNA specialist with the Department of Justice, said at today’s news conference.

Authorities said today that in March 2011, a "first-degree relative" was the source of the confirming sample that led investigators to Troyer.

That relative, whom they described as a "close male relative," had committed a crime that resulted in the collection of DNA evidence. Authorities would not reveal the relative's name.

After the relative's sample was evaluated and uploaded into a state database, investigators found a link to the DNA profile from the crime scene. Investigators described the link between the relative and Troyer as "a father, son, immediate relative" connection.

Police were able to obtain a sample from Troyer from the Orange County coroner's office and make a match. They said investigators also found that a relative of Troyer's lived close to the Klaas home and that a man fitting his description had been reported by witnesses at the time of the crime.

Medley, who was present at the news conference today with Klaas' two sons, thanked authorities for their hard work.

"It's been a long road. ... I speak for the family and all of us, it's just nice to close the book on this," he said. "DNA, what a wonderful thing!"