A Missouri teenager faces prison time for fatally shooting her 16-year-old girlfriend during a game of Russian roulette. Prosecutors allege that the teen fired the shot while spinning the gun on her finger, as detailed by the victim’s mother.

“That’s when the gun went off, taking my daughter’s life,” said Nicole Pettis, the mother of Mattison Johnson, in an interview with NBC affiliate KSDK. Mary Cornelius, now 19, received a seven-year prison sentence after pleading guilty to first-degree involuntary manslaughter on Thursday.

At the time of the shooting on January 3, Johnson’s younger sisters, aged 9 and 11, were present in the home. It was one of these sisters who discovered the tragic scene, according to Pettis.

“My nine-year-old daughter called me,” Pettis recounted. “She was frantic, saying, ‘Mommy, you need to come home.’ She could barely get the words out but finally said, ‘Mommy, Matti was shot.’”

Pettis claims her daughter was in an abusive relationship with Cornelius, who was blamed for mishandling the gun during the game. She has openly expressed doubt that the shooting was accidental.

“I will seek justice for my daughter,” Pettis declared when Cornelius was initially charged. “I wish nothing more than for her to sit in prison, to be haunted by the memory of what she did to my daughter every single night. May my daughter’s image weigh heavily on her conscience forever.” Pettis added, “God forgive me, but I hope my daughter haunts her.”

Cornelius reportedly apologized in court at her sentencing last Thursday, as did her sister. “A child is gone, so you’ll have to take responsibility,” the sister said, according to KSDK.