Sandra Fernandez had recently started a new job before police say her former boyfriend waited nearby and killed her.

TUSTIN, Calif. — A Hawthorne man has been charged with murder after police said he waited outside his former girlfriend’s Tustin workplace and fatally shot her as she left for home after a training session.

Juan Marquez, 47, is accused in the May 14 killing of Sandra Fernandez, 42, of Anaheim, a mother of three whose family said she had just begun a new job in the area. The case moved from a shooting call near Yorba Street and Medford Avenue to a cross-border arrest within two days, ending with Marquez held without bail in Orange County Jail and prosecutors adding allegations that could raise the stakes of any conviction.

Officers were called shortly after 6 p.m. to the busy Tustin intersection after reports of gunfire. When they arrived, they found Fernandez unresponsive on a curb with gunshot wounds. Paramedics pronounced her dead at the scene. Police later said investigators believed Marquez had been waiting near the workplace before Fernandez came outside. Witnesses described a man wearing all black running from the area and leaving in a dark, older-model sedan. Police said Fernandez was walking to her car when she was shot. Her family said she had finished training at the new job and was starting a chapter she had been excited about.

The investigation quickly focused on Marquez, whom police identified as Fernandez’s former boyfriend. Detectives said they confirmed his involvement and learned he had crossed into Mexico through the San Ysidro Port of Entry after the shooting. By May 16, police had obtained an arrest warrant. U.S. Customs and Border Protection officers detained Marquez that afternoon as he tried to return to the United States through the same border checkpoint. Tustin detectives then took custody of him. Police said the shooting appeared to be isolated and that no ongoing threat to the public had been found. Authorities have not publicly released a motive.

Prosecutors later charged Marquez with murder and added a special circumstance allegation of lying in wait, along with a sentencing enhancement tied to the discharge of a gun causing death. The allegations place the case beyond a standard murder filing and signal that prosecutors plan to argue the killing was planned rather than sudden. Police said Marquez attacked Fernandez near her workplace, while prosecutors said the killing happened at Yorba Street and Medford Avenue. Court records available through public reports did not immediately show a future hearing date, and no plea was reported in the days after the filing.

Fernandez’s relatives described her as a single mother working to support her family. A fundraiser organized by her niece, Melitza Uribe, said Fernandez had a 5-year-old child, a 14-year-old child and an older son finishing college. The page said the family was not prepared for funeral and burial costs and did not know of any life insurance policy. It described Fernandez as a hard-working mother, daughter, sister and aunt who “had her life ahead.” The fundraiser said money would go toward a proper goodbye and payments for funeral arrangements. It also listed a May 24 kermes planned to help raise funds for services.

Family members also spoke publicly about the shock left by Fernandez’s death. Uribe said Fernandez brought happiness, helping hands and the steady presence of a great mother to those around her. She said the arrest gave relatives part of an answer but not the reason they still wanted. “We don’t know the motive. We don’t know why,” Uribe said. Asked what she would say to Marquez, Uribe said she had nothing for him. “Only God knows what he deserves,” she said. “He can take care of that. My heart is going to show no hatred.”

At the workplace, co-worker Cassie Rossel said Fernandez had made an impression in a short time. “Even though it was just under a month, she already was making good relationships and having a great impact,” Rossel said. The detail deepened the loss for those who had just begun to know her. Police have not said whether Fernandez had reported threats before the shooting, whether a protective order existed or whether investigators recovered the gun. Officials also have not said how long Marquez was in Mexico before he returned to the border checkpoint.

The case now rests with prosecutors and investigators as they prepare the next court steps. Marquez remains in Orange County Jail without bail, charged with murder in Fernandez’s death. The next milestone is the scheduling of formal court proceedings, where the charges and special circumstance allegation will begin moving through the Orange County criminal court system.

Author note: Last updated June 17, 2026.