OTTAWA — A two-and-half-year investigation of the Toronto police found that “systemic discrimination” within the force enabled a serial killer to murder eight gay men, mostly of Middle Eastern or South Asian descent, over a span of seven years.

Several times the police interviewed the killer, Bruce McArthur, who was convicted in 2019, but did not link him to the deaths and released him — allowing him to continue his killing spree.

“There was institutional resistance to the notion that these cases night be linked and that a serial killer might be preying on” Toronto’s L.G.B.T.Q community, Gloria Epstein, a retired justice of the Ontario Court of Appeal, wrote in a report released on Tuesday. “This systemic failure is perhaps the most troubling.”

The investigation found that the police force repeatedly failed to enter evidence linking the killings to Mr. McArthur into case-tracking software.

The report makes 151 recommendations, among them proposals to allow civilians within the Toronto police force to coordinate missing persons investigations; to centralize those inquiries under one police unit; and to conduct them in concert with public health, social service and not-for-profit community groups.