The employee who shot five co-workers, and himself, to death at the Molson Coors brewery Feb. 26 had been targeted by a racist prank five years ago, according to news reports.

Anthony Ferrill, an electrician, had been notified in 2015 by the Molson Coors HR department that a noose was placed in or near his locker at work. Ferrill was not on duty that day and did not actually see the noose, and it was never determined who put it there, a Molson Coors spokesperson said in a statement.

The five victims ranged in age from 33 to 61, and all but one had been with Molson Coors for at least six years. The Milwaukee Journal-Sentinel reported that Ferrill had had unspecified “ongoing tensions with at least one co-worker,” but did not say whether those tensions were race-related. Molson Coors said it was not aware of any formal complaints about racial harassment made by Ferrill.

The case has been bandied about on social media, with Facebook having to flag one false claim that Ferrill went on the shooting spree immediately after being fired for complaining about the noose.