Manitoba RCMP Chief Supt. Scott Kolody said an autopsy is being performed today that may "provide insight into the cause" of the child's death.
Cassandra's body was found on Monday on the Garden Hill First Nation, after she had been missing for a week.
Community members have said they believe she was attacked by some kind of animal, possibly a bear. But police have not backed up that theory.
"We do not have a confirmed cause of death," Kolody told reporters in Winnipeg.
He said the RCMP's serious and major crimes units are involved in the investigation and officers are in the community.