Dylan Chandler entered the plea for the killing of 37-year-old Joseph Keith Aman of Baltimore, who was shot once in the head and pronounced dead at the scene on January 28.

Prosecutors said Chandler was called into a supervisor's office to discuss workplace performance issues. A witness told investigators that Chandler and Aman were talking when the witness heard a gunshot and turned to see Chandler pointing a handgun at Aman. The witness disarmed Chandler and held him until police arrived.

Investigators said Chandler admitted to shooting Aman because he "snapped." State's Attorney Anne Colt Leitess said the evidence indicated the killing was not planned in advance.

"Investigators believe the defendant did not premeditate or plan to commit murder, but rather killed the victim following being reprimanded for workplace conduct," Leitess said in a statement.

Chandler is scheduled to be sentenced on December 15 in Anne Arundel County Circuit Court. The case has drawn attention to workplace safety at the sprawling Linthicum defense campus, where thousands of employees work on sensitive national security programs.

The guilty plea brings a measure of closure to a case that shocked colleagues and highlighted the potential for violence in routine employment disputes. Aman's family and co-workers have not publicly commented on the plea.