MARTINEZ — A man was convicted of murdering a transgender woman in a crime that went unsolved for nearly 30 years, until a DNA match, authorities said.

James Grimsley, 57, was convicted of second-degree murder in the Dec. 2, 1994 killing of 28-year-old Terrie Ladwig, a Concord resident who was strangled in her home during a violent struggle. Authorities say that Ladwig invited Grimsley to her home for a romantic encounter and that things got violent during their interaction.

“I know everybody who knew Terry back then is glad this finally saw a courtroom and that the jury saw the truth and recognized that this man was responsible,” Contra Costa Deputy District Attorney Satish Jallepalli, who prosecuted the case, said in an interview. He said the murder was a tragic reminder of the “vulnerability” of the transgender community, and “underscores that this is something that’s been a reality for the trans community for a long time.”

Prosecutors pinpointed two possible motives — that Ladwig resisted Grimsley’s sexual advances or that Grimsley discovered Ladwig was transgender and became enraged. During trial, Grimsley testified they had a consensual sexual encounter and that he left, but never knew Ladwig was transgender until his arrest.

That claim, though, was contradicted by Grimsley’s ex-girlfriend. She told authorities Grimsley used an offensive term while admitting to killing a transgender person and said he was concerned he’d end up on the TV show “Unsolved Mysteries” someday, according to court records.

The case did go unsolved until late 2022, when cold case homicide investigators took a secret DNA sample from Grimsley, which was later matched to blood from Ladwig’s turtleneck and skin cells underneath her fingernails, according to court records. Grimsley was identified as a possible suspect thanks to genetic genealogy, a technique made famous by the Golden State Killer murder investigation.

Grimsley testified that he had an open cut and must have inadvertently bled on Ladwig during their encounter. Police believe the two met when Grimsley stopped in the Bay Area during the course of his employment as a long-haul trucker.

In his confession to his ex-girlfriend years after the murder, Grimsley allegedly told her he’d strangled a transgender person, and showed her the scar to prove it, authorities said. The woman only came forward after Grimsley was arrested in early 2023, and said she was scared of retribution, according to police.

After his arrest, Grimsley spent more than two years behind bars before heading to trial in April. His public defender didn’t immediately return a request for comment.

Grimsley, an Oregon native who lived in the Salt Lake City area, was still employed as a trucker at the time of his arrest. Police say his job could have brought him to Contra Costa County in the 1990s.

Ladwig lived on Adelaide Street in Concord with her husband, who worked in the U.S. Navy. The Contra Costa Times reported in 2004 that Ladwig called her husband to report someone was trying to break into the house, and that when he rushed home from a base in Bangor, Wash., he discovered her body. Police said at the time there did not appear to be forced entry into the home.