A 21-year-old Rancho Santa Margarita woman is dead after deputies say she was killed in a street race allegedly involving her own brother near Trabuco Hills High School in Mission Viejo. Shalia Deciderio died at the scene of a solo-vehicle crash on Thursday, August 20, near Los Alisos Boulevard and Mustang Run, and both her 20-year-old brother and the other driver involved now face felony manslaughter charges.
Orange County sheriff’s deputies responded to the crash at around 9:40 p.m. that night, according to NBC Los Angeles. Officials said Deciderio was found dead at the scene, while the driver of the vehicle that crashed, 20-year-old Mission Viejo resident Jaimie Rojas, was taken to a hospital for treatment. Deciderio’s brother, 20-year-old Aiden Deciderio, was driving the other vehicle allegedly involved in the race and was not injured.
A preliminary investigation found that street racing caused the crash, the outlet reported. Both Rojas and Aiden Deciderio were arrested on suspicion of vehicular manslaughter with gross negligence. Per MyNewsLA.com, Aiden Deciderio remained at the crash scene the night of the collision and was booked into Orange County Jail the following day, while Rojas was first transported for medical treatment before booking.
Legal Exposure Under California’s Street Racing Law
The reason both men face identical charges — even though only one vehicle crashed — traces back to a 2023 change in state law. Under Senate Bill 1472, known as Ryan’s Law, California’s Penal Code Section 192(c)(1) was expanded so that participating in an illegal speed contest or street race resulting in death qualifies as gross negligence, the standard needed for a gross vehicular manslaughter charge, according to the Dordulian Law Group. That means prosecutors can pursue felony charges against every driver who took part in a race, regardless of who was actually behind the wheel of the car that crashed.
A conviction under that statute carries a potential state prison sentence of two, four, or six years, plus a fine of up to $10,000 under Penal Code Section 193(a), per Eisner Gorin LLP. The charge is classified as a wobbler, meaning prosecutors can pursue it as either a felony or a misdemeanor depending on the circumstances of the case.
Crash Site Sits Steps From High School Entrance
The stretch of roadway where the crash occurred sits directly outside Trabuco Hills High School, a Saddleback Valley Unified School District campus serving roughly 2,400 students, according to the district. Mustang Run functions as the school’s main entrance roadway, meaning the alleged race unfolded on a street built to funnel student traffic in and out of campus.
The City of Mission Viejo has previously invested in pedestrian safety upgrades along that same Los Alisos Boulevard and Mustang Run corridor, including crosswalk refuge islands and curb extensions funded through regional grants, according to city records from 2022. Los Alisos Boulevard serves as a primary arterial connecting Mission Viejo to Rancho Santa Margarita, where Shalia Deciderio lived.
Second Fatal Crash Involving Young Driver in Two Weeks
This is the second fatal crash in Mission Viejo tied to a young driver in less than two weeks. On August 8, an 18-year-old driver struck and killed a 60-year-old pedestrian near Pacific Crest Drive and Glenwood Drive, a case Hoodline previously reported was also being investigated as a possible felony manslaughter case.
Both crashes were assigned to the Orange County Sheriff’s Department’s Major Accident Investigation Team, a specialized unit that handles fatal and complex collisions using digital scene mapping, speed calculations, and mechanical vehicle inspections across contract sheriff cities in South Orange County, according to the department. The unit is now examining the Mustang Run crash to determine exact speeds and reconstruct how the race unfolded.
The case also lands amid a broader crackdown on street racing across the county. Between 2022 and early 2025, the Orange County District Attorney’s Office filed nearly 2,000 criminal cases tied to reckless driving, street racing, and street takeovers, according to Voice of OC. Statewide, the California Highway Patrol logged nearly 6,000 street takeover and racing incidents in 2021 alone, per Wallin & Klarich, a surge that prompted multi-agency task force enforcement across Southern California and, eventually, legislative changes like Assembly Bill 2000, which expanded speed contest prohibitions to parking lots and off-highway facilities and authorized courts to suspend driver’s licenses for up to six months.
Investigators have not said whether toxicology results are expected or whether prior street racing complaints had been logged near the Mustang Run corridor. Anyone with information about the crash is asked to contact the OCSD Major Accident Investigation Team at 949-425-1860, or to reach Orange County Crime Stoppers at 855-TIP-OCCS.
