Security Guard ‘Snaps’ and Kills Coworker During Performance Evaluation at Aerospace and Defense Company

A routine workplace evaluation at a major defense contractor in Maryland turned deadly Wednesday after a security guard allegedly opened fire on a coworker during a tense meeting.

Police say 26-year-old Dylan Blake Chandler, a contract security worker, shot and killed 37-year-old Joseph Keith Aman at a facility operated by Northrop Grumman in Anne Arundel County. The shooting happened late Wednesday afternoon.

According to court documents, Aman — also a security guard at the site — had pulled Chandler aside to discuss concerns about his job performance. Records show Chandler was facing possible reprimand or termination at the time of the meeting.

A third security guard was present during the conversation. Authorities say that after Chandler allegedly shot Aman, that coworker immediately intervened, disarming Chandler and preventing further violence. Police credited the guard’s quick actions with stopping the situation from escalating.

“As you can imagine, it’s very traumatizing for this to happen in the workplace,” Anne Arundel County Police spokesperson Justin Mulcahy said during a press conference. “It was isolated and ended very quickly, and we are thankful for the intervention of the third security guard who was there to take him into custody.”

Another witness told investigators they heard a loud bang and then saw Chandler holding a handgun while Aman collapsed from an apparent gunshot wound.

Detectives say that after being taken into custody, Chandler admitted he “snapped,” telling police he believed Aman was not being held accountable for his own actions.

Both Aman and Chandler were contracted employees working under the private security firm Allied Universal. In a statement, the company said it was “deeply saddened by the loss of our employee” and extended condolences to Aman’s family and friends, adding that it is cooperating fully with investigators.

Chandler has been charged with first- and second-degree murder and is being held without bond. A preliminary hearing is expected to take place next month.

Northrop Grumman, one of the largest defense contractors in the United States, said it is assisting law enforcement as the investigation continues.