Updated

An “alleged serial killer” in Toronto was previously interviewed by detectives and then let go years before he was arrested and charged in the deaths of six people, new reports say.

Toronto Police have now launched an internal investigation into the matter after detectives currently working the case said they didn’t find out about Bruce McArthur’s prior questioning until after his arrest in January. The former landscaper and shopping mall Santa Claus is facing six first-degree murder charges, with some of his alleged victims’ remains being found in garden planters at a home where he previously worked.

“We know this information will be disappointing to some members of the community,” Toronto Police spokesperson Meaghan Gray told the Toronto Star on Tuesday. “In addition to listening to their concerns, we have always said we are open to a public inquiry into these investigations, and Chief Saunders has already taken steps to consider what areas can be reviewed right now, during the ongoing investigation.”

The new reports from The Globe and Mail and the Toronto Star offer conflicting information on the exact date of the interview, with one saying it happened in 2013 and the latter say it was between 2014 and 2017. But both reports raise questions about what police knew about McArthur in the years leading up to his arrest.

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Clockwise from left: Majeed Kayhan, 58; Dean Lisowick; Soroush Marmudi, 50; Selim Esen, 44 and Andrew Kinsman, 49. (Toronto Police Services)

The Globe and Mail, citing a source with knowledge of the interview, says it occurred during the Project Houston investigation, which looked into the disappearances of three men in Toronto's Gay Village neighborhood, two of which McArthur was later charged with killing.

The source said detectives had linked McArthur to two of the men through dating apps and brought him in for questioning after receiving an anonymous tip.

The Toronto Star, citing similar sources, said the interview happened between the closure of Project Houston in 2014 and the beginning of another investigation in 2017 that resulted in McArthur’s arrest. It also said the interview was over a matter unrelated to the missing people, but did not disclose what exactly.

Detective Sgt. Hank Idsinga told The Globe and Mail in January that McArthur was not a suspect during Project Houston.

"Until we can establish that there has been foul play, we can attach a criminal offence to foul play, that's when someone would become a suspect,” he said.

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Feb. 13, 2018: People hold a candlelight vigil to remember the victims of alleged serial killer Bruce McArthur in Toronto. (AP)

Idsinga then told the newspaper on Sunday that he "will not be commenting on who we may or may not have spoken to."

The revelations come days after Toronto police released a picture of an unidentified deceased man believed to be another victim of McArthur’s while announcing that a seventh set of dismembered remains has been found.

"I do not want to release this picture and I'm doing so as a last resort," Idsinga told reporters Monday, asking for the public’s help in identifying the man.

To date, investigators have identified three sets of remains found at the Toronto home where McArthur worked as a landscaper: Andrew Kinsman, 49, Soroush Mahmudi, 50 and Skandaraj Navaratnam, 40.

In addition to murder charges McArthur faces in their deaths, he is also facing charges for the presumed deaths of Selim Esen, 44, Majeed Kayhan, 58 and Dean Lisowick, either 43 or 44, according to the Associated Press. Police are not ruling out more victims.

McArthur, 66, has not entered a guilty plea and his next court appearance is set for March 14.