lee allan bonneau , 6 , was attacked by a 10-year-old boy and beaten to death with a rock and a stick in august 2013 in saskatchewan , canada .
the killer , identified only as l.t. , has not been charged because of his young age .
he told friends after the slaying he had witnessed a ` big guy ' murder a boy .
l.t. later admitted he was the killer and pleaded , ` do n't tell on me '
the child had a history of violence , including one incident when he killed a pregnant dog and her puppies .
lee bonneau had been removed from his birth mother 's care two and a half months before the killing and placed with foster family .