The kid was autistic. Apparently the officer who shot was stalking the kid’s Dad’s fiancé prior to the murder as well.

"Mardis was hit by five bullets, also struck in the head and chest. He was initially thought to have died instantly, according to the coroner for Avoyelles Parish. However, it is now known that six-year-old Mardis was alive for an additional seven minutes while lying in his father's truck."