SAN DIEGO — Police have identified the man suspected of shooting and killing a 79-year-old in San Diego this week, saying the suspect was already behind bars and now faces a murder charge.

Authorities also released the name of the victim for the first time Friday, sharing the updates in a news release.

Jose Quirin, 79, walked into a Pacific Beach McDonalds on Mission Bay Drive early Tuesday morning suffering from a gunshot wound and looking for help, according to the San Diego Police Department. Workers flagged down police, and both officers and paramedics tried to save the elderly man, but he died a short time later at a local hospital.

Detectives investigating the case eventually identified 21-year-old Francisco Villegas as the man suspected of gunning down Quirin. Villegas was already in county jail due to a probation violation, according to SDPD. Now officials have also booked him on a murder charge.

Officials suspect the younger man of shooting Quirin on Morena Boulevard in the Bay Ho neighborhood. That’s about 2 miles away from the McDonalds where the victim later sought help.

Quirin was parked in front of the building where he worked when he was approached by a gunman, now believed to be Villegas, who “likely attempted to carjack his vehicle,” police said in Friday’s update.

“When the victim did not immediately surrender his vehicle, the suspect fired at least one round from a firearm through the driver’s side window glass, striking the victim and causing his injuries.”

Officers arrested Villegas due to the probation violation on Wednesday, then identified him as the murder suspect one day later, police said.

Officials urged anyone with information about the killing to call the department’s Homicide Unit at 619-531-2293 or San Diego County Crime Stoppers at 888-580-8477.