The body of Phoenix Sinclair, seen here in an undated photo, was discovered in 2006 on the Fisher River reserve. (Family photo)

In videotaped evidence played Friday at the Phoenix Sinclair murder trial in Winnipeg, the girl's sobbing stepfather told police he knew he had "made a big mistake" and would have to pay for it when he saw the child's lifeless body on the basement floor of their home.

Karl McKay and girlfriend Samantha Kematch, the five-year-old's mother, have pleaded not guilty to first-degree murder in the 2005 slaying of Phoenix on Manitoba’s Fisher River Indian reserve.

They are also accused of trying to pass off another little girl as their own, after Phoenix died, to convince welfare authorities Phoenix was still with the family — partly to apply for benefits in her name.

In a videotaped interview with police played for jurors at the couple’s joint murder trial, McKay said he tried to resuscitate Phoenix when he saw her body on the floor.

In the video, McKay sobs as he tells an RCMP officer he wishes the incident had never happened. He told police he knew he had made a big mistake and would have to pay for it.

The day she died, McKay told police he told Phoenix to "shut up" and threw her about "three or four feet" on the basement floor.

But he said she landed on a pile of clothes and was still breathing when the couple left to visit McKay's father nearby.

Body wrapped in plastic

"I didn't want to kill the little kid," McKay said. "Once in a while, I would give her a licking. I didn't intend to do serious harm."

After five minutes of performing CPR, McKay said the couple took Phoenix upstairs and gave her a bath to try to revive her.

When it didn't work, he said they took her back downstairs and wrapped her in plastic.

They drove her out beyond the Fisher River garbage dump and buried her in a shallow grave, he said.

"I wish it had never happened," McKay said, crying. "Maybe now she can rest in peace."

McKay said he grew up in abusive situations and was one of 26 children in his family. He called himself the "black sheep of the family" and lived in many foster homes.

"I know what it's like to get a licking, stuff like that," he said in the taped interview.

"[Did] you get beat up lots?" the RCMP interrogator asked.

"Yeah, every day," said McKay.

The tape shows McKay saying both he and Kematch would beat the little girl. He added that both adults became frightened when they found the child was not breathing.

In earlier testimony this week, two of McKay's sons, aged 15 and 18, testified that both parents beat the little girl. Jurors were told McKay would stomp on her until she stopped crying.

One of the boys said Phoenix was sometimes brutally beaten with a metal rod and shot with a pellet gun "just for the hell of it."

Phoenix died in June 2005, but her body wasn't found until months later.

With files from the Canadian Press