Toronto police said an autopsy determined Keayanna Chambers died as a result of pressure on her neck and chest.
While earlier reports indicated the girl had been badly burned, police would not confirm those allegations.
“I'm not going to comment on this child's injuries,” Det. Sgt. Chris Buck told reporters Sunday.
“All I'm going to say at this point is that the trauma to the child's body was visible to the officers who attended.”
Police received two 911 calls shortly after 1 p.m. Friday indicating “unknown trouble” at the east Toronto split-level residence the mother and daughter shared for about the last three months, according to neighbours
The girl was found in a third-floor room and pronounced dead on scene, while her mother was located close by and taken into custody.
Det. Sgt. Buck said Charlene Chambers is not known to police and has no known history of mental illness. She's currently unemployed, but does have family supports within the Greater Toronto Area, he said.
“These kinds of cases are very sensitive. They're a tragedy to all of us, but in particular they're a tragedy to the families involved,” he said.
“They've not only lost a young member of their family, they've also lost the mother of that child to the judicial system... It's a very difficult situation for them. It's obviously filled with mixed feelings.”
Ms. Chambers appeared briefly in court Saturday. She's scheduled to appear in court again Tuesday morning via video remand.
Police were seeking a search warrant to conduct a full forensic examination of the home and were expected to remain on scene for one or two more days.