Police in Ontario have determined the torso recovered from the lower Niagara River belongs to a Caucasian woman between 20 and 40 years old.

Police say the preliminary post-mortem indicates the woman had a pierced navel and at least one caesarean section scar.

Passersby spotted the body - without a head or limbs - floating in the river near the Rainbow Bridge in Niagara Falls and alerted authorities Wednesday afternoon.

Police say the woman was the victim of a homicide, but won't release cause of death until the autopsy results are complete.

Investigators and forensic experts say the torso is not related to the investigation in the Toronto-area involving the slaying of Guang Hua Liu.

Liu's body parts - but not her torso - were found earlier this month west of Toronto in Mississauga and near her home in east-end Toronto.

(The Canadian Press)