Charges have been upgraded to first-degree murder for the two people accused in the slaying of a seven-year-old girl.

Donna Irving, the girl's legal guardian, and her boyfriend Warren Johnson, had both been charged with second-degree murder after Toronto police found Katelynn Sampson dead in her west-end apartment a month ago.

A woman had called 911 in the early morning hours of Sunday, August 3 to report that a child was choking on food.

Police and paramedics arrived at the apartment at 105 West Lodge Avenue about 2:30 a.m. and found the girl dead.

She also showed signs of physical abuse.

The child's mother, Bernice Sampson, had given legal custody of her daughter to Irving earlier this year so she could sort out some personal issues.

Court documents showed that a background check on Irving, 29, was not conducted.

Child advocates have called for an inquiry into the case since the little girl's death. They also call for changes to the child-welfare system to make background checks mandatory for all potential guardians.