The older sister of Dominic Russo is criticizing the parents of Mackenzie Shirilla following renewed attention to the fatal crash that claimed the lives of 20-year-old Russo and 19-year-old Davion Flanagan.

Prosecutors argued Shirilla, who was 17 at the time, intentionally drove her car at nearly 100 mph into a brick wall in Strongsville, Ohio, on July 31, 2022, in an attempt to kill her boyfriend amid their strained relationship. Both Russo and Flanagan were killed in the crash; Flanagan was in the backseat.

In 2023, Shirilla was found guilty of double murder and other charges and sentenced to two concurrent 15-years-to-life sentences with the possibility of parole after 15 years.

The case has returned to the spotlight following the May 15 release of Netflix’s The Crash, which features interviews with the victims’ loved ones, Shirilla’s parents and Shirilla herself from prison.

Russo’s sister, Christine Russo, says she believes Shirilla’s parents, Steve and Natalie Shirilla, have not shown enough remorse while continuing to defend their daughter in the documentary.

“It’s all for show,” Christine, 37, tells PEOPLE.

Shirilla’s parents have faced criticism over remarks made in The Crash, including comments defending their daughter’s marijuana use, dismissing allegations that she bullied other students in school, and suggesting she suffered a medical emergency and lost consciousness at the time of the fatal crash, leaving her with no memory of it all.

“There is a fine line between defending your kids,” Christine adds. “And they created a monster — they’re monsters themselves.”

In the documentary, Steve and Natalie claim they have since gathered evidence supporting their daughter that was not presented in court, while disputing allegations that Mackenzie had threatened to crash her car with Dominic inside weeks before the deadly wreck. They pointed to alleged text messages they say show Mackenzie telling Russo’s mother that Russo was “trying to end my life.”

Mackenzie’s attorneys are now asking the Ohio Supreme Court to review her case, arguing she may have been acquitted if paperwork had been filed on time, according to court records obtained by Cleveland 19 and reviewed by PEOPLE. Her previous appeals have been denied.

“She’s always appealing her conviction,” Christine says. “She can’t take accountability or responsibility.”

Christine has since launched a petition calling for “Dom and Davion’s Law,” urging Ohio lawmakers to update the state’s Son of Sam laws for the digital age amid concerns about Mackenzie potentially profiting from social media.

“Since the documentary aired, our family has had to relive this tragedy publicly over and over again,” the petition reads. “What hurts even more is seeing how modern social media culture allows violent offenders to gain attention, followers, donations, publicity, and influence from the crimes that destroyed families like mine.”

Christine has also launched a GoFundMe for the Change the Game for Dom Foundation, which aims to help underprivileged children access opportunities to play basketball.

Meanwhile, Flanagan’s family has continued honoring his legacy through a barber scholarship fund established in his name, which has raised over $135,000 through GoFundMe since 2023.