 The family of a black man killed by Hyatt Regency Hotel security guards in Milwaukee is calling for murder charges. CBS's Allison Keys. Cell phone videos show four security guards holding Devontae Mitchell down as at least one of them kneels on his back. Stay down! Please stop fighting! I witnessed Sean Moore tell CBS News. After they turned him over, I knew he was gone. He adds. I never thought that I was witnessing a murder.