Don’t let past discrimination complaints by an obviously troubled employee keep you from ensuring. Even vague threats can justify firing a potentially dangerous employee. Few judges will see that as retaliation.
Just make sure you keep good, contemporaneous records as your investigation proceeds.
Recent case: Adolfo, a heterosexual married man, worked in sales for designer brand Gucci America. He complained to HR that two of his supervisors were sexually harassing him because of his gender and his straight orientation. For example, one supervisor allegedly made comments about his own gay lifestyle, including describing forays into gay bars where he pole-danced. The other supervisor allegedly told Adolfo he thought Adolfo must really be gay.
Shortly after, several co-workers went to their supervisors and HR to express concerns about their safety. They claimed Adolfo told them “something big” was going to happen, that he sometimes made shooting motions with his fingers and that he talked frequently about shooting people. After an investigation, Adolfo was fired for making threats.
He sued, alleging he was really fired for complaining about anti-straight bias.
The court didn’t buy it, concluding that the supervisors’ sexually oriented comments weren’t severe or frequent enough to constitute sexual harassment. It said well-documented co-worker fears about Adolfo’s behavior were a legitimate reason to terminate him. (Mendez-Nouel v. Gucci America, No. 10-CIV-3388, SD NY, 2012)
Final note: Threats require prompt action. Adolfo was suspended pending the investigation.