Story highlights Gunman reportedly threatened doctor because of a perceived wrong

The gunman once worked at the facility where the doctor treated combat vets

(CNN) A psychologist who was shot dead at a Texas veterans' hospital filed a complaint in 2013 saying his killer had threatened him, an FBI agent said Wednesday.

Dr. Timothy Fjordbak, 63, was killed Tuesday by Jerry Serrato, a former Army soldier who worked for a brief time at the hospital as a check-in clerk. Serrato killed himself after shooting the doctor.

FBI Special Agent in Charge Doug Lindquist said Fjordbak had reported to police in October 2013 that Serrato verbally threatened him at a grocery store. Serrato approached Fjordbak, who didn't recognize him, Lindquist said.

The nature of the threat was "I know what you did, and I will take care of it," the agent said.

Peter Dancy, the facility's director, said there is no indication the two had a professional relationship when Serrato worked at the clinic.

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