why did hotch leave criminal minds

Thomas Gibson, who played Aaron Hotchner ("Hotch") on Criminal Minds, left the show because he was fired in 2016 following an on-set physical altercation with a writer-producer. This incident came after reports of problematic, anger-prone behavior, including previous disputes that led to mandatory anger management. As a result, Hotch was written out of the series in Season 12, with the storyline explaining that his character went into the Witness Protection Program to protect his son, who was being targeted by a serial killer. Hotch then chose to become a full-time father rather than return to the BAU team. Gibson expressed regret over leaving and thanked fans and colleagues, but the firing was based on both personal and professional issues behind the scenes.