Dog the Bounty Hunter's Cop Son Sues Police Dept. For 'Retaliatory' Firing

Dog the Bounty Hunter's son Garry Chapman -- who was fired, then reinstated, from a police force in Alabama last year -- is suing the department ... He says they only disciplined him to teach him a lesson for calling out a dirty cop.

Remember ... Chapman's employment was terminated last year after his involvement in a fatal high-speed car chase. He was later reinstated, but he says he should've never been fired in the first place.

In court documents, obtained by TMZ, Chapman alleges the police department, along with Priceville, Alabama, Mayor Sam Heflin, used the tragic incident as an opportunity to smear his name and get rid of him -- something Chapman alleges they were working on for some time.

Chapman claims it started when he filed a formal complaint regarding the unprofessional conduct of a fellow officer. In the papers, Chapman alleges the departmental leadership dismissed the complaint, questioning why he was so concerned with the actions of another officer, and began to drudge up "previously undisclosed, minor issues to begin papering his personnel file."

In the documents, Chapman claims things escalated when he blew the whistle on an officer who intended to take a departmental K-9 as his personal pet when he left the department.

When the tragic accident came along, Chapman says the mayor and police department purposefully made him the face of it, thus vilifying him and causing him "catastrophic reputational harm."

Chapman says he subsequently lost out on a promotion and has been unable to secure other employment in law enforcement because no agency wants to hire an officer whose name is in national headlines for a fatal incident.