Handwritten Message: Mackenzie Shirilla’s mom and dad revealed a pr!son letter from their daughter, with one last sentence now disturbing everyone

After reaching a speed of nearly 100 mph, the sedan, captured by security cameras, clipped a sign standing in front of a commercial building and slammed head-on into a brick wall with a force that sent shock waves through the still-dark sky.

First responders found Russo crumpled in the front passenger seat of the wreckage and Flanagan, his friend, stacked on top of him. “Oh my God,” an officer could be heard saying on police radio. “Driver, a 17-year-old female, still breathing, wedged in there. Two [passengers] are going to be DOA. . . . Rest in peace, buddy.” As a LifeFlight helicopter touched down to transport the driver to a hospital, another officer somberly commented, “This is the worst crash I’ve ever seen.”

Investigators spent months trying to figure out what led to the collision that Shirilla narrowly survived, with three broken ribs, serious organ injuries and loss of memory of the accident. Although Shirilla had been at a party prior to the crash, toxicology tests ruled out drug and alcohol impairment, and a forensic automotive investigator determined that no mechanical failures occurred. According to prosecutors, that left only one possibility: Shirilla, a recent high school graduate and content creator who hoped to become a fashion model, intentionally drove her car into a wall in order to kill Russo, her partner in a rocky relationship, and their friend Flanagan, who happened to also be in the car.

Arrested in November 2022 and charged with aggravated homicide, Shirilla — whose crimes are chronicled in the new Netflix documentary The Crash — was convicted of double murder on Aug. 14, 2023. Days later, Cuyahoga County Common Pleas Judge Nancy Margaret Russo (no relation to the victim) handed down two concurrent sentences of 15 years to life. “This was not reckless driving,” Judge Russo says in courtroom footage seen in the documentary. “This was murder. . . . [Shirilla] morphs from a responsible driver to literal hell on wheels.”

The daughter of Natalie and Steve Shirilla, Mackenzie grew up in a suburb of Cleveland and attended Strongsville High School. Like most teens, she was active on social media. She frequently posted TikToks of her dancing to favorite songs, modeling new looks and smoking marijuana with friends. At 17, with her parents’ consent, she moved in with Russo, an older student she met in her freshman year who had graduated and become an entrepreneur. On social media, a friend of Shirilla’s described him as a “baller” who indulged her taste for designer-label accessories.

But the relationship had its ups and downs. Dominic’s mother, Christine Russo, told police that she received an urgent message from her son saying he was in a car with Shirilla, who was driving erratically and dangerously, and that he needed immediate help. During closing arguments at Shirilla’s trial, Cuyahoga County assistant prosecutor Tim Troup explained to the court, “Mackenzie had threatened to crash a car with Dominic two weeks before she [actually] did. In criminal cases we call that prior calculation.”

Shirilla’s lawyer argued that she remembered nothing about the crash because she suffers from POTS, a blood pressure disorder that could have caused her to black out. But Troup and other experts argued that Shirilla was in full control of the vehicle. “If she had passed out, her foot would have eased off the gas,” says Troup. Instead, data recovered from the car’s electronic instruments showed that, after slowing down to ease around a corner near the crash site, the driver had engaged the gas pedal 100 percent until the moment of impact. Experts made another chilling discovery: Three seconds before the crash, the steering wheel turned sharply and the car shifted from drive to neutral and back to drive again. Says Troup: “I think the boys were trying to save their lives.”

Currently incarcerated at the Ohio Reformatory for Women in Marysville, Shirilla remains a polarizing figure. In recorded phone conversations with her mother, she speaks in coded language resembling pig latin, saying that her family should tell prosecutors she had suffered “a seizure” that caused the crash. In other conversations, she insists that “I don’t need to be rehabilitated” in prison and that she is the “third victim” in the accident.

Shirilla says in The Crash that “it’s been hard every day” of life at the Ohio Reformatory for Women. “I try to wake up and be the best person I can be [and] stay out of trouble.”

Kat Crowder, a former inmate who served time alongside Shirilla, tells PEOPLE she seemed upbeat: “She would do her makeup, make jewelry, customize shoes and hats.” But she had an attitude toward prisoners she felt were “less than” her, Crowder claims.

“Nothing about [the crash] was intentional, because that’s not my character,” she says in a prison interview in The Crash. “I’m not saying I’m innocent. I was a driver of a tragedy, but I’m not a murderer.”

But the families of her victims are hardly convinced. Dominic’s sister Christine claims that Shirilla continues to make money from hersocial media posts even behind bars, and she is now working with Ohio lawmakers to draft new legislation banning influencers from profiting from their crimes. And speaking after Shirilla formally apologized to the families in court in 2023, Davion’s sister Davyne said, “That was the worst apology I think I’ve ever heard in my life. I know when someone’s being fake.”

• With reporting by NICOLE ACOSTA and CHRIS SPARGO