The lead RCMP investigator in the Phoenix Sinclair homicide case told a public inquiry into the child's death that he had hoped witnesses were lying when they detailed the abuse she suffered.

The testimony from Cpl. Robert Baker on Thursday was the latest the Phoenix Sinclair inquiry heard about what happened after the five-year-old girl was killed in 2005 on the Fisher River First Nation.

Her biological mother, Samantha Kematch, and Kematch's boyfriend, Karl McKay, were convicted in 2008 of first-degree murder in Phoenix's death.

While Phoenix died in the summer of 2005, it wasn't until March 6, 2006, that child and family services authorities received a tip that the little girl was dead. The RCMP was subsequently contacted.

Phoenix's remains were found, wrapped in plastic, in an unmarked shallow grave near the First Nation's landfill on March 18, 2006.

Baker told the inquiry on Thursday that two witnesses he interviewed told him about the abuse Phoenix had suffered at the hands of McKay and Kematch, and the eventual disposal of her body in the woods.

"Unfathomable that that kind of abuse could have happened," Baker testified.

"It was unimaginable. That part of me led me to hope that maybe it wasn't true, that perhaps we could still find her."

Baker said by the time Phoenix's remains were found, animals had made off with some parts of her body because she was buried in a shallow grave.

Mother showed 'no emotional response'

During his testimony, Baker recalled arresting Kematch and feeling disturbed that she did not show emotion over Phoenix's death.

"I asked her … when she buried Phoenix Sinclair, 'Did you have a chance to give her a kiss goodbye?' There was no response. No emotional response," he said.

McKay and Kematch had lied to police, and that was why it took so long to find Phoenix's body, Baker told the inquiry.

Baker also testified that child and family services (CFS) officials told him he could not have access to the three closed files they had on Phoenix, citing privacy laws.

Phoenix had spent much of her short life in foster care or with family friends in Winnipeg.

The inquiry has already heard that social workers sometimes lost track of who had care of the girl, failed to monitor the family and closed Phoenix's file without seeing her.

When asked why he thought it took so long for anyone to realize Phoenix was missing, Baker said it was because McKay and Kematch were very deceptive and they moved around a lot, which created jurisdictional issues for authorities.

McKay's niece saw blood on stairs

Baker said during the investigation, officers found in McKay's backyard some pellets from a BB gun that was used on Phoenix.

However, they found no blood on the floor of McKay's basement, where the little girl had been kept, because it was painted over by then.

Allison Kakewash, one of McKay's nieces, testified earlier on Thursday that she saw "drips of blood" on the basement steps during a visit to the house.

McKay was seen running up and down those steps in an apparent cleaning frenzy, while Kematch was weeping by a computer, Kakewash recalled.

"I felt this bad feeling, like as if Wesley killed somebody," Kakewash told the inquiry.

When Kakewash asked where Phoenix was, McKay said the child was in Ontario with her father "because she was a bad little girl," the inquiry was told.

A week prior to that incident, Kakewash said she saw Phoenix, with a blanket over her head and her body covered in marks, alone in a dark room in the house.

McKay ordered Kakewash to shut the door of the room, the inquiry was told.

On another occasion, Kakewash said she took her own baby to Kematch's and McKay's house for a play date with Phoenix, but it ended when Phoenix knocked another child onto the floor.

McKay grabbed Phoenix roughly, called her a "bitch" and threw her into the dark room, Kakewash testified.

When asked why she did not report the abuse Phoenix was facing to CFS authorities, Kakewash said she was scared of McKay, whom she described as "wicked."