TRUE CRIME NEWSMan Walking With Wife on Anniversary Celebration Sustains Fatal 'Internal Decapitation' in Street Collision Caused by Young Woman, 22
Sysillia Kianna Morrison Montes De Oca was convicted of vehicular manslaughter after hitting a couple with her car in 2022 on their anniversary which resulted in the man's death.
Sept. 17 2026, Published 8:13 p.m. ET
A 22-year-old woman was convicted after colliding with a couple, which resulted in the husband's death and the wife suffering severe injuries.
The accident occurred in August 2022, when Sysillia Kianna Morrison Montes De Oca was just 18 years old.
She was reportedly driving a 2009 Volkswagen Jetta shortly after 9:30 p.m. when she hit 60-year-old Stanley Isaacs and his wife, Catherina, with three other passengers in the car.
Stanley Isaacs, 60, died after suffering an 'internal decapitation' after Sysillia Kianna Morrison Montes De Oca hit him and his wife Catherina with her car.
Per The Orange County Register, Isaacs was sent flying after being hit and suffered an “internal decapitation,” skull fracture, snapped spine and “smashed ribs” from the accident and was later pronounced dead.
Young Woman Convicted in the Death of 60-Year-Old Man After Fatal Collision
Stanley Isaacs was reportedly flung into the air from the force of the collision.
The couple had reportedly just finished their anniversary dinner at a nearby restaurant in Laguna Beach and were crossing the street when the accident occurred.
Per the outlet, she had smoked marijuana that evening, although it is unclear how much time had passed between her drug use and the accident.
She also reportedly told her friends in the car that she was going to speed up just before the collision happened.
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Sysillia Kianna Morrison Montes De Oca fled the scene after crashing into Stanley Isaacs and his wife, Catherina.
Instead of stopping to check on the couple and help, she reportedly fled the scene in her car.
On Thursday, September 10, Montes De Oca was found guilty of gross vehicular manslaughter, hit-and-run with permanent and serious injury and failing to stop at a hit-and-run with injury or death, all felony counts, in a California court.
Sysillia Kianna Morrison Montes De Oca reportedly had a friend help her hide the car.
Per the publication, she later returned to the scene with her friend but did not disclose her identity.
She also had one of her friends, Jack Francis Bannigan, hide the car for her at the time.
He also pleaded guilty earlier this year to being an accessory after the accident due to his involvement in trying to hide evidence.
Per the prosecutors, after the accident, she kept searching online for more information on the fatal accident she had caused.
Deputy District Attorney Justin Kim said during the trial, “It was not an ordinary mistake.”
Sysillia Kianna Morrison Montes De Oca's sentencing is scheduled for November 13.
“We all know she fled the scene,” he added.
Defense attorney Mike Molfetta argued in court that Montes De Oca was “catatonic” after the accident and only left the scene at the urging of her friends.
“They need you to hate her to get a conviction,” he further alleged, referring to the prosecutors.
She ultimately turned herself in to the authorities about two weeks later, per Law & Crime.
Montes De Oca’s sentencing is scheduled for November 13.
