A five-year-old Manitoba girl suffered months of abuse before dying at the hands of her mother and the mother's boyfriend — who then covered up the slaying before applying for welfare in the dead child's name, a Winnipeg jury has heard.

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

Human remains, believed those of Phoenix Sinclair, 5, were found on the Fisher River reserve, 150 kilometres north of Winnipeg in 2006. It is believed she was killed in 2005, although the body was not discovered until months later.

Phoenix's biological mother, Samantha Kematch, and Kematch's former boyfriend, Karl McKay, have pleaded not guilty to charges of first-degree murder.

In his opening statement to jurors Wednesday, Crown attorney Rick Saull alleged both Kematch and McKay were equally responsible for the forcible confinement, abuse and death of the child.

"This little girl died as the result of months of abuse," Saull said. "After the final blows were administered, she was left to die on a cold basement floor."

Suffered dozens of injuries

Sinclair spent most of her young life in foster care before being placed back with her mother in 2004. Court was told she died on June 11, 2005, but was not reported missing until nine months later.

Saull told jurors the Crown will show the girl suffered dozens of injuries between April and June 2005 while she was in the couple's care.

He said Kematch and McKay made a feeble attempt to revive the child, even though they were just a few kilometres from a medical facility. After the girl died, he said, her plastic-wrapped body was buried in a wooded area, using a neighbour's shovel.

Later the couple applied for and received welfare payments in Phoenix's name.

Eventually McKay showed the burial spot to RCMP, which by then was covered in snow.

The couple's trial is expected to last until mid-December.

The child's death sparked a massive review of Manitoba's child welfare system.

With files from the Canadian Press