Toronto police have laid a new murder charge against an alleged serial killer who is believed to have preyed upon men from the city's gay community for years, bringing the total number of people he's accused of killing to six.

Det. Sgt. Hank Idsinga said Friday that Bruce McArthur has been charged with first-degree murder in the death of 40-year-old Skandaraj Navaratnam, who disappeared from the city's gay village in 2010.

Idsinga said more charges are expected to be laid against 66-year-old McArthur, noting that police were combing through hundreds of past cases in search of potential links.

"There's multiple outstanding murder cases that we're looking at," Idsinga told a news conference. "There's hundreds of outstanding missing persons occurrences that we're looking at. There's even some ... occurrences where there's been a sudden death that we're looking at."

Navaratnam's remains were among those of six people recovered from planters at a residential property where McArthur worked as a landscaper, Idsinga said.

Three of the six sets of remains have now been identified using fingerprint analysis and dental records, Idsinga said, adding other confirmed victims are 49-year-old Andrew Kinsman and 50-year-old Soroush Mahmudi.

McArthur has also been charged with first-degree murder in the presumed deaths of 44-year-old Selim Esen, Majeed Kayhan, 58, and Dean Lisowick, either 43 or 44.

Idsinga said the investigation into McArthur's activities, which he previously described as unprecedented, comprises hundreds of Toronto police officers as well as other Canadian and international forces.

Police have interviewed some of McArthur's past known associates, but Idsinga said evidence unearthed so far indicates he acted alone.

McArthur was charged Jan. 18 with the murder of Kinsman and Esen, who went missing from Toronto's gay village in 2017. Late last month, police laid three more first-degree murder charges against McArthur related to the disappearances of Kayhan and Mahmudi, as well as the death of Lisowick who had never been reported missing.

Police said they have searched multiple properties in the Toronto area, including excavating the back yard at the home where the six sets of remains were found.

Idsinga said police may return to that scene in warmer weather to see if police dogs have further success in scouring the area.

He said police have also identified at least two properties for potential excavation, but said forensic test results are needed before they can proceed. Officers have also been combing through McArthur's central Toronto apartment for a month and expect to remain there for weeks longer, he added.