It is likely that McArthur will face charges in relation to the man's death.
Detective Sergeant Hank Idsinga of the Toronto Police Service said Kanagaratnam was born in Sri Lanka but moved to Canada in 2010.
At least seven sets of remains, including Faizi's, have been recovered from planters located at a Toronto home where McArthur once worked as a landscaper, police have said.
Investigators identified the eight victim - Kirushna Kumar Kanagaratnam - last week after releasing a photograph of the dead man "as a last resort".
Police say there are no links between Kanagaratnam and "Gay Village" of Toronto.
Idsinga said Kanagaratnam was never reported missing and was not identified until after police released an image that generated hundreds of tips. The identification of Kanagaratnam was confirmed with assistance from an worldwide government agency, Idsinga said.
Later that month, he was charged with the first-degree murder of Majeed Kayhan, Soroush Mahmudi, and Dean Lisowick.
"I think we've all seen in the media so-called experts who tell us that serial killers don't start in their late 50s and their 60s", Idsinga said.
Idsinga said police are looking at cold cases as far back as 1975, but have not found evidence linking McArthur to historic cases.
On January 18, 2018, McArthur was arrested on suspicion of murder. Police have not released a cause of death for any of the men.
Kanagaratnam's dismembered remains were discovered in planters with the other victims on the Mallory Cres. property where McArthur was a landscaper. He had no direct family in Canada and was never reported missing.
"We have lots of searches left to do as the weather gets warmer", Idsinga said. Police investigated his death as part of Project Houston, which ran from November 2012 to April 2014 and probed the disappearances of three men who went missing from Toronto's gay village.
Kayhan's remains have not yet been found.
Police believe Kanagaratnam was killed sometime between 3 of September and 14 of December, 2015.