Firefighter Craig Warren committed suicide on July 31, 2009, the day the city gave him to resign or be fired, according to The Statesman Journal.
The lawsuit also says that the 20-year veteran of the fire department suffered psychological problems following the response to several traumatic calls.
In early 2009, a switch in psychiatrists resulted in a medication mistake, causing behavioral problems, according to the report.
During that time, the department was investigating Warren for alleged inappropriate comments made to other firefighters.
"It's our opinion that the way the city conducted the investigation of Mr. Warren, especially when they became aware that he was having some emotional difficulties, was very cruel," family attorney Jaime Goldberg told the newspaper.
The family is seeking $4.15M in damages.
