Mark D. Henning, 48, died on December 17, 2015, after a violent confrontation inside the Dearborn Heights Justice Center in Michigan. Around 8:45 a.m. that Thursday, Henning entered the building that houses the 20th District Courthouse and the police department, attempted to bypass the security checkpoint and charged at a security guard while brandishing a large kitchen knife. Witnesses said Henning pulled the knife from his back pocket and ignored multiple commands to drop it.

As Henning lunged at the guard, a former Dearborn Heights police officer, the guard fired multiple times, fatally wounding him. The building and nearby schools were placed on lockdown and the Michigan State Police took over the investigation. Investigators concluded Henning acted alone; no other suspects were sought. He had been arrested less than three weeks earlier after a traffic crash and found in possession of clonazepam without a prescription, and he was scheduled to appear in court the following Monday. The motive for the attack remained unclear and the case was referred to the Wayne County Prosecutor’s Office for review.