(CNN) A noose was once placed on the locker of the man who shot and killed five coworkers at the Molson Coors complex in Milwaukee before taking his own life, the company said.

The noose was found on Anthony Ferrill's locker in 2015, Molson Coors spokesman Adam Collins said. The company has not been able to identify who placed it there.

"It was a disgusting act five years ago, and remains disgusting today," Collins said.

Anthony Ferrill

Collins said Ferrill, 51, who is African American, was not working the day the noose was placed on his locker

"Our HR team notified him of the incident. It was investigated fully," he said. "No camera footage was available to show who placed it on the locker, we offered HR and Security services to the employee, we talked to the brewery leadership team in Milwaukee about the issue and we ensured everyone knew about our confidential paths to share discrimination or harassment complaints."

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