Niagara Regional Police say they have completed their search of the whirlpool to the Niagara Falls.
Investigators are calling it a homicide, but say it has been difficult to determine where exactly the torso may have entered the water and where the crime scene may be located.
Police say the search will resume if new information becomes available.
Passersby alerted authorities Wednesday after discovering the floating torso in the river.
Preliminary post-mortem results indicate the torso belongs to a Caucasian woman between 20 and 40 years old.
The examination also indicated the woman had a pierced navel and at least one caesarean section scar.
It's believed the torso had been in the water for four to 10 days before it was found and police hope to find more of her remains to help identify her.
Meanwhile, police in the Toronto-area are still looking for a number of body parts — including a torso — belonging to Gua Huang Liu.
The 41-year-old single mother's head and limbs were found in Mississauga and Toronto in the mid-August.
Her estranged boyfriend, Chun Qi Jiang, has been charged with second-degree murder in connection with the death and he is to next appear in court later this month.
Niagara police say this latest discovery is unrelated to the Liu case.