The gunman who killed five co-workers at the Molson Coors Brewery in Milwaukee last week came to work one day in 2015 to find out that a noose had been placed on his locker, the company disclosed Tuesday.

Police have not said what might have sparked the rampage by 51-year-old electrician Anthony Ferrill on Feb. 26, who died of an apparent self-inflicted gunshot wound.

The company said Ferrill never actually saw the racist symbol, as it was spotted and removed before he got to work, the company said.

"Our HR team brought it to his attention," Adam Collins, chief communications and corporate affairs officer for Molson Coors, told reporters, according to NBC affiliate WTMJ in Milwaukee.

Collins said of the noose incident, "There aren’t words to describe that; it’s awful."

Read the full story on NBCNews.com