Authorities sought to identify the seventh set of remains by releasing a photograph of the man in what was considered a controversial move.
"I did not want to release this picture and I am doing so as a last resort", said Det. "I've never done this before-I do it with great hesitation".
The serial killer's spree can be traced back to 2010.
Idsinga said investigators believe the man was dead when the photo was taken. He admitted that the image of the man had been enhanced and altered to "remove artifacts", and analyzing the photo's history in Photoshop shows just how much it's been altered from the original.
Fingerprint and dental analysis has not been successful, police say. The smudge tool which blends and blurs together selected parts of the photo was used 76 times.
The revelation comes just one day after investigators took what they called the rare step of releasing the photo in the hopes that a member of the public could identify the middle-aged bearded man.
"We need to put a name to this face and bring closure to the man's loved ones", Idsinga said, according to Vice.
The source says the new set of unidentified remains were found in a planter at the same Toronto property where six other sets were found in large planters.
Last month investigators confirmed that the remains of Kinsman, Mahmoudi and Navaratnam along with the remains of three unidentified men found in tubs for flowers on a plot of Mallory Crescent, where MacArthur kept the equipment for improvement of gardens.
McArthur is charged in their deaths, as well as the presumed deaths of Selim Esen, 44, Majeed Kayhan, 58, and Dean Lisowick, either 43 or 44. "It's a bit of a misconception", he said.
The Mallory Crescent property has been ground zero for investigators, with at least six other sets of remains found in planters there.
The latest set of remains were discovered in a planter in Toronto in an area where McArthur had previously been a landscaper.
Dr. Michael Pollanen, Chief Forensic Pathologist for the Province of Ontario, said the causes of death are pending further studies.
Examiners have also not yet determined cause of death on numerous victims, with decomposition severely hampering their ability to get a complete picture.
He added that they won't be releasing a cause of death until the investigation is concluded.
Police are looking at unsolved missing person cases to determine if there are connections to McArthur and are running down tips that have come in from around the world.
Toronto police believe they've found another victim in a series of murders in the city's Gay Village neighborhood.