VENTURA, Calif. (AP) — A 73-year-old man has been charged in the strangulation deaths of three Southern California women in 1977 after cold case detectives obtained a DNA match, authorities said Thursday, adding they believe there could be more victims.

Warren Luther Alexander of Diamondhead, Mississippi, made his first court appearance Thursday but arraignment on three counts of first-degree murder was postponed to Aug. 21, the Ventura County District Attorney’s Office said. He remained jailed without bail.

Alexander’s case was assigned to the county public defender’s office. A telephone message was left at the office seeking comment on the case.

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

All the California victims were killed by “ligature strangulations,” District Attorney Erik Nasarenko said at a news conference. All were sex workers in Ventura County, northwest of Los Angeles, and frequented an area known for sex trafficking, he said.

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.

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“While believing these three crimes were indeed connected, leads ran cold and detectives were unable to identify who was responsible for these horrific murders,” Nasarenko said.

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

A 2006 query of the database had failed to find a match.

North Carolina news media reported that Alexander was arrested in the Cobb case in March 2022. That case had yet to proceed to trial, said Joey Buttitta, spokesperson for Ventura County prosecutors.

Alexander lived in Oxnard in the late 1950s and ‘60s, attending elementary, middle and high schools, and returned in the 1970s, Nasarenko said.

From the 1970s into the early 1990s Alexander was a long-haul, cross-country truck driver, Nasarenko said.

“We believe there may be additional victims both locally and other states,” he said. “This is an ongoing investigation, and we will continue to pursue all leads that become available. This is not in any way closed.”