VENTURA, Calif. (AP) — A 73-year-old man has been charged in the 1977 strangulation deaths of three Southern California women after investigators made a DNA match in unsolved cases, authorities said Thursday, adding that they believe there may be more victims.

Warren Luther Alexander of Diamondhead, Mississippi, made his first court appearance Thursday, but his arraignment on three counts of first-degree murder was postponed until Aug. 21, the Ventura County District Attorney’s Office said. He remained incarcerated and could not be released on bail.

Alexander’s case was turned over to the county public defender’s office, where a phone message was left requesting a statement on the case.

Alexander was extradited from Surry County, North Carolina, to California on Aug. 6 to await arraignment in an unsolved 1992 murder case, the office said.

All of the victims in California were killed by strangulation, District Attorney Erik Nasarenko said at a news conference. All of the victims were sex workers in Ventura County, northwest of Los Angeles, and frequented an area known for human 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 in the city of Oxnard on September 8 of the same year, followed by Lorraine Rodriguez, 21, on December 27 in an unincorporated area.

“Although it was believed that these three crimes were indeed connected, the traces ran dry and investigators were unable to identify the person responsible for these gruesome murders,” Nasarenko said.

The DNA match with Alexander came last year when DNA evidence was uploaded to a national database, the district attorney said. The genealogy investigation 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 database query from 2006 found no match.

North Carolina news media reported that Alexander was arrested in the Cobb case in March 2022. There has not yet been a trial in that case, said Joey Buttitta, spokesman for the Ventura County District Attorney’s Office.

Alexander lived in Oxnard in the late 1950s and 1960s, attended elementary, middle and high school, and returned in the 1970s, Nasarenko said.

From the 1970s to the early 1990s, Alexander was a long-distance truck driver, Nasarenko said.

“We believe there may be additional victims both locally and in other states,” he said. “The investigation is ongoing and we will follow up on any leads that come our way. This is far from over.”