Christa Engles, 26, died from a gunshot wound inside her Tulsa, Oklahoma, home in November 2014. A U.S. Army veteran and active reservist, she was reportedly changing her one-year-old daughter’s diaper when her three-year-old son found a loaded semi-automatic handgun that had been stored under a couch. The child picked up the large-caliber weapon and it discharged, a single shot striking Engles in the head.

Her mother, who lived in the home, found Engles seriously wounded and the two children covered in blood; the toddler repeatedly said Mommy shot. Engles was taken to St. John Medical Center and was pronounced dead at 5:38 p.m. The Tulsa Police Department investigated and ruled the death an accident. No arrests were made and no suspects were named.

If anyone knew Christa or was in the neighborhood at the time, any details about how the firearm came to be stored there could help clarify what happened.