Police said Juan Marquez fled to Mexico after Sandra Fernandez was shot near her car.
TUSTIN, CA — A Hawthorne man accused of killing his former girlfriend near her Tustin workplace was arrested Saturday at the U.S.-Mexico border after fleeing the country, police said.
Juan Marquez, 47, was booked into the Orange County Jail on suspicion of murder in the death of Sandra Fernandez, 42, of Anaheim. Tustin police said Fernandez was shot Thursday evening near Yorba Street and Medford Avenue, a busy area close to businesses and traffic. Marquez was being held without bail as detectives continued to review the shooting, the flight to Mexico and the events that led to his arrest.
Officers were called at about 6:11 p.m. Thursday after reports of gunfire near Yorba Street and Medford Avenue, police said. When they arrived, they found Fernandez with fatal gunshot wounds. She was pronounced dead at the scene. Police said Marquez had left before officers arrived. Witnesses told investigators they saw a man dressed in black run from the area and leave in a dark, older-model sedan. The shooting happened near Fernandez’s workplace, and investigators later said Marquez had waited nearby before the attack. Police described him as Fernandez’s former boyfriend and said the shooting appeared to be targeted.
Fernandez was found near a small white SUV, according to early accounts from the scene. Family members said she was a mother and had recently been working when the shooting occurred. Some reports identified the workplace as Families Together, a nonprofit health and community services group in Orange County. Police have not released a full timeline of Fernandez’s final minutes, and they have not said whether Marquez spoke to her before the gunfire. They also have not released a motive. The known facts place Fernandez near her car after work and Marquez near the area before the shooting, according to investigators.
Detectives identified Marquez as the suspect after the shooting and learned he had crossed into Mexico through the San Ysidro Port of Entry, police said. Investigators obtained an arrest warrant. On Saturday afternoon, U.S. Customs and Border Protection agents detained Marquez as he attempted to re-enter the United States through the same border region, authorities said. Tustin police detectives then took custody of him and booked him in Orange County. The department thanked federal agents and other law enforcement partners for helping locate and arrest him after he left the country.
The killing shook a part of Tustin where offices, shops and homes sit close to major roads. The area around Yorba Street and Medford Avenue is not far from 17th Street, a well-traveled corridor in central Orange County. Police said the shooting was an isolated incident and that there was no continuing threat to the public. Still, the case drew concern because it unfolded in daylight near a workplace and because investigators said the suspect had been in a past relationship with the victim. Fernandez’s family began raising money for funeral costs after her death.
Marquez had not made an initial court appearance as of the first police announcement of his arrest. Jail records and court filings are expected to provide the next public steps in the case, including any formal charge filed by prosecutors, an arraignment date and whether Marquez enters a plea. A murder booking allows authorities to hold him while prosecutors review reports from detectives, witness statements, border records and any evidence collected from the shooting scene. Police said the investigation remained active, and they asked anyone with information to contact investigators.
Family members and community members remembered Fernandez as a mother whose death left children and relatives grieving. Police did not release detailed family statements, but relatives described the shooting as sudden and devastating. The scene also left witnesses with the image of a fast-moving attack near parked cars and traffic. Investigators are expected to examine surveillance video from nearby businesses, license plate records, border crossing information and phone data as they work to build the timeline from the shooting to Marquez’s return to the United States.
Marquez remained in custody without bail after his arrest. The next milestone is expected in Orange County court, where prosecutors will decide the formal charges tied to Fernandez’s killing.
Author note: Last updated May 18, 2026.