Matching up DNA found to the five victims identified so far could take months, lead investigator Sergeant Hank Idsinga said.
"It's going to take a long time, but we're well-equipped to investigate... and hopefully we'll be able to bring closure to families," he told a news conference.
Bruce McArthur, 66, was arrested earlier this month for two murders and was charged Monday with three additional homicides after skeletal remains were found "hidden in the bottom of (large) planters" at a Toronto property he used for storage.
Police are now scouring more than 30 properties around the city where he is known to have worked, and "where people might be buried," Idsinga said Monday.
They are also following up on "dozens of tips" received since authorities announced they were investigating a possible serial killer.
The tips pointed to more sites, officials said.
McArthur had been under suspicion since September in connection with the disappearance of victim Andrew Kinsman, with whom he had been involved.
According to local media, police made a quick decision to enter McArthur's home and arrest him on January 18 when they saw a young man enter his apartment. Police found the man tied up on a bed, but unharmed.
He was spared jail time but was prohibited him from soliciting gay prostitutes and from possessing "poppers" -- a recreational drug used in sexual encounters -- and was ordered to undergo anger management.
One of his last alleged victims, Dean Lisowick, was a homeless man, and is believed to have worked as a prostitute.
All of the alleged victims went missing from a predominantly gay neighborhood in downtown Toronto over the past five years.
The disappearance of one of the murdered men was also believed to be connected to two other missing persons cases. McArthur has not been charged in those disappearances.
Authorities are now reviewing missing persons cases dating back to at least 2010, and asking anyone who employed McArthur to do garden work to come forward.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)