Juan Marquez is accused of killing Sandra Fernandez after she left work and then fleeing to Mexico.
TUSTIN, Calif. — Prosecutors have charged Juan Marquez with murder and alleged he lay in wait before fatally shooting Sandra Fernandez outside her Tustin workplace, moving the case into a more serious legal stage.
The filing against Marquez, 47, of Hawthorne, followed a fast-moving investigation into the May 14 killing of Fernandez, 42, of Anaheim. Police said Marquez was Fernandez’s former boyfriend, waited near her workplace, shot her as she left for home and then crossed into Mexico. He was arrested May 16 while returning to the United States and is being held without bail in Orange County Jail. A possible motive has not been released.
The charge filed May 19 includes murder, a special circumstance allegation of lying in wait and an enhancement alleging discharge of a gun causing death. Those allegations frame the case around planning, position and timing. Prosecutors will have to prove the charge and any added allegation in court. Police said the shooting happened near Yorba Street and Medford Avenue, where Fernandez was found with fatal gunshot wounds. The filing came after detectives said they had identified Marquez, obtained an arrest warrant and coordinated with federal officers at the border.
The first call to police came shortly after 6 p.m. Thursday, May 14. Officers arrived at the Tustin intersection and found Fernandez unresponsive on a curb. Paramedics pronounced her dead. Witnesses described a man wearing all black fleeing the area and driving away in a dark, older-model sedan. Investigators later said Marquez had laid in wait near Fernandez’s workplace and killed her after she left for home. Family members said Fernandez was leaving a training session connected to a new job. Other local reports said she was found near or behind a small white SUV, close to where she had parked.
Police said Marquez crossed the U.S.-Mexico border through the San Ysidro Port of Entry after the shooting. The case then shifted from a local homicide scene to a regional search involving a border checkpoint. By Saturday afternoon, May 16, U.S. Customs and Border Protection officers detained Marquez as he attempted to re-enter the United States. Tustin detectives took him into custody after the border stop. Police said he was booked on suspicion of murder and held without bail. Authorities have not said what Marquez did between the shooting and his return to the border, or whether anyone helped him.
The lying-in-wait allegation aligns with the police account that Marquez waited near Fernandez’s workplace before the shooting. It also raises questions investigators may need to answer in court, including how long he was there, what evidence places him at the scene, whether cameras captured his arrival or departure, and how detectives connected him to the vehicle described by witnesses. Officials have not publicly released surveillance images, a firearm recovery or forensic details. They also have not said whether Fernandez had previously contacted police about Marquez or whether there were known threats before the attack.
Fernandez’s relatives said she had just started working in the area and was trying to provide for her children. A fundraiser created by her niece, Melitza Uribe, described Fernandez as a hard-working mother of three with a 5-year-old child, a 14-year-old child and an older son finishing college. The page said the family was raising money for funeral and burial expenses because relatives were not prepared to lay her to rest. It said a kermes was scheduled for May 24 to help raise funds for services. The organizer said payments would go directly toward funeral arrangements.
Family members also gave public statements that showed the emotional side of the case prosecutors are now bringing into court. Uribe said Fernandez was known for happiness, helping others and being a devoted mother. “There’s so much you can see from the outside,” Uribe said. “You know, the happiness, the helping hands, the always being there, being a great mother.” Uribe said relatives were still left without the reason for the killing. “We don’t know the motive. We don’t know why,” she said. Asked what she would say to Marquez, she said she had nothing to say.
At Fernandez’s new workplace, co-worker Cassie Rossel said Fernandez had already made an impact in less than a month. “Even though it was just under a month, she already was making good relationships and having a great impact,” Rossel said. That account gave the case a second timeline beyond the criminal investigation: Fernandez had begun a job, completed training and was walking toward her car when police say the attack happened. The shooting interrupted the start of that job and turned a workday departure into the scene of a homicide investigation.
Investigators have not announced a motive, and public reports did not immediately list a future hearing date. The next major development is expected in court, where prosecutors must begin proving the case they have charged. Marquez is being held in the Orange County Jail without bail while the murder charge and special circumstance allegation await the next court steps.
Author note: Last updated June 17, 2026.