On January 3, 2025, 16-year-old Mattison Matty Johnson was fatally shot inside her home on the 1400 block of East Grand Boulevard in the College Hill neighborhood of St. Louis. Responding officers arrived about 1:37 p.m. and found Mattison deceased. An 18-year-old woman known to the victim, Mary Cornelius, who was present during the shooting, told police she had been holding the firearm when it discharged; she was charged with first-degree involuntary manslaughter and armed criminal action. Initial accounts described the shooting as accidental, with witnesses saying Cornelius had been negligently handling the gun.

Mattison’s mother, Nichole Pettis, disputes that description, saying the pair had been in an abusive relationship and that Cornelius had been playing with the weapon despite being asked to put it away. Pettis said two younger daughters, ages 9 and 11, were in the home and heard arguing earlier that morning. Mattison was remembered by family as a bright, ambitious teen who hoped to become a nurse; she had recently returned to school and worked at a local laundromat. A memorial service was held and a GoFundMe was set up to help with funeral costs and the family’s pursuit of justice.

Does anyone have information about Mattison, the household that day, or the parties involved that could help investigators and the family?