04/09/2015 02:48 EDT | Updated 06/09/2015 09:59 EDT

Boy who severely beat younger child didn't react to news of death: investigator

REGINA - An RCMP investigator says a 10-year-old boy who severely beat a younger child on a Saskatchewan reserve didn't react when he learned his actions had been fatal.

Cpl. Donna Zawislak told a coroner's inquest Thursday into the death of six-year-old Lee Bonneau that the 10-year-old was lying on his mother's lap, sleeping in a police interview room, when she woke him up to explain that Lee was dead.

"(He) was very calm," Zawislak testified, adding that the boy's mother broke down. "(He) began comforting his mother."

Lee was found with head injuries in a wooded area on the Kahkewistahaw reserve in 2013. He had last been seen walking with an older boy outside a recreation complex while his foster mother was playing bingo.

Saskatchewan's children's advocate determined that the 10-year-old, whose name is covered by a publication ban, had behavioural issues and probably should not have been in the community unsupervised. Because he was under 12, he could not be charged under the Youth Criminal Justice Act.

Zawislak said she learned from the boy's social worker that he had been hearing voices.

Forty-eight people were interviewed over the course of the investigation, she said.

"People weren't surprised that he potentially could be responsible for what happened."

She said the boy had trouble focusing when he was interviewed by police.

"He was trying to open the door, he was crawling around on the floor," she said, adding that he had scratches and scrapes on his body. "He provided conflicting information."

Zawislak said the boy knew the location of Lee's injuries and identified weapons including a stick and a rock that were used in the beating. She added that there was a human bite mark on Lee's forearm.

A medical expert said Lee's injuries were similar to those seen in high-speed car crashes or a 10-metre fall.

Dr. Shaun Ladham, who is a forensic pathologist, said the cause of Lee's death was blunt force trauma to the head causing multiple skull fractures.

"That does not happen easily," he said, adding that "considerable force" was used.

The inquest also heard from Alicia Ward, the child protection worker in charge of Lee's case. He had been in the care of the Ministry of Social Services for less than three months when he died.

The inquest has heard there were concerns about domestic violence in Lee's home, and the boy was taken into care after his mother told a Social Services worker she wanted to commit suicide.

Under questioning from coroner's council Sonya Guiboche, Ward acknowledged her office was dealing with a heavy case load at the time and needed more staff.

In a report released last year, Children's Advocate Bob Pringle said the boy who killed Lee didn't receive the help he needed.

Pringle said his investigation found nine child protection concerns reported to the Yorkton Tribal Council Child and Family Services, but as far his office could determine, two concerns were never investigated. Other investigations were delayed by months.

Pringle also said the RCMP had alerted the agency to the boy's behavioural issues. Mounties believed he was involved in a break and enter in May 2011 where a pregnant dog and her unborn pups were killed.