Assault to an Employee

My lil brother was falsely accused of a ********** act at work. So a investigation took place and he was called in at work when asked to write a statement he asked the guy who was investigating him to show him proof that he was involved but no evidence was provided. When he refused to write the statement and decided to resign he was assualted by the securities and customers with out the manager or whoever was in charge stopping it. This hurts me because I found him in a bad state and he was crying. I would like the head office to undertake this investigation and look it up.