It's no secret that Hank Voight is a dirty cop. Along with a whole lot of lying, intimidation, and manipulation; Voight also isn't afraid to get physical. There are a couple of times that Voight takes the law — and those he believes deserve something more than an arrest — into his own hands. One such incident occurs in Season 3 when the Chicago P.D. capture a human trafficker. Once the suspect is in custody, Voight goes after him with an iron poker in the interview room referred to as "the cage." Things get intense when Voight attempt to get the truth out of him and it isn't easy to watch (via YouTube). 

While the iron poker is one of the more memorable incidents of physical abuse, it wasn't unprecedented. In Season 2, Voight finds himself in the middle of an armed robbery alongside his son's pregnant girlfriend, Olive; per Screen Rant. When the robbers threaten to murder Olive, Voight reluctantly hands over all of the money being stored in his safe. But after the robbers get away, Voight tracks down not only his kidnappers, but also everyone associated with them. In true Voight style, his interrogation methods take a turn for the abusive and he breaks more than a few bones. This sort of vigilante justice has become Voight's M.O. on the show, but that doesn't make it any easier to watch.