(CNN) -- Toronto police made a gruesome discovery Wednesday when they opened a suitcase that two boaters on Lake Ontario had towed back to shore.
Inside was a badly decomposed human torso, its gender unknown.
Investigators are in touch with two other police departments investigating the recent discovery of body parts in their jurisdictions, said Toronto Det. Leslie Dunkley.
"It is a very serious case and a very serious incident and we are going to do our best to get to the bottom of it," Dunkley told reporters Wednesday afternoon.
The floating suitcase was spotted 1.5 miles offshore and was brought to Bluffer's Park, police said. A post-mortem examination is scheduled for Thursday.
Authorities have been investigating the death of Guang Hua Liu, whose body parts were found in mid-August in several places. The investigation began along the Credit River in Mississauga, west of Toronto.
Liu's torso is still missing.
CNN affiliate CTV said Liu, 41, was a Canadian citizen of Chinese descent who once owned a spa in Toronto. She lived in Scarborough and was the single mother of three.
Peel Regional Police, near Toronto, last week said an arrest was made in Liu's death.
Wednesday's discovery of the suitcase came one week after a woman's torso was found in the Canadian portion of the Niagara River.
Niagara Regional Police said the unidentified white woman, likely in her mid-20s to early 40s, was a homicide victim. The torso was recovered near the Rainbow Bridge close to Niagara Falls.
The Niagara River case is not related to Liu's death, police have said.
The Niagara River connects Lake Erie and Lake Ontario.