VENTURA, Calif. (AP) — A 73-year-old man pleaded not guilty Wednesday in a Southern California cold case alleging he strangled three women in 1977, the Ventura County District Attorney’s Office said.

Warren Luther Alexander of Diamondhead, Mississippi, was arraigned on murder charges filed after use of DNA in the investigation of the long-unsolved killings.

Alexander was extradited to California on Aug. 6 from Surry County, North Carolina, where he was awaiting prosecution in a 1992 cold case killing.

All the California victims were sex workers in Ventura County, District Attorney Erik Nasarenko said earlier this month.

Kimberly Fritz, 18, was found dead in the city of Port Hueneme on May 29, 1977. Velvet Sanchez, 31, was found dead on Sept. 8 that year in the city of Oxnard, followed by Lorraine Rodriguez, 21, on Dec. 27 in an unincorporated area.

A match to Alexander occurred last year when DNA evidence was uploaded into a national database, according to the district attorney.

Investigative genealogy had identified Alexander as a suspect in the North Carolina case of 29-year-old Nona Cobb, whose body was left along Interstate 77. Alexander was arrested in the Cobb killing in March 2022 but that case has yet to proceed to trial.

Authorities said Alexander lived in Oxnard in the 1950s and ’60s, and returned in the 1970s. He was a cross-country truck driver from the 1970s into the early 1990s.