(CNN) -- Shiping Bao, the medical examiner who changed his mind on crucial aspects during his testimony at George Zimmerman's trial, has been fired.

But he's not going down without a fight.

Bao has hired a lawyer and is hinting at a lawsuit.

Bao was let go from his job as the associate medical examiner for the the Volusia County, Florida, Medical Examiner's Office last week, officials said Wednesday.

Authorities provided a copy of his termination letter, but did not specify a reason. The letter says Bao was given a choice to resign. He didn't. So, he was terminated Friday.

Bao's lawyer filed a complaint against the county, CNN affiliate Central Florida News 13 reported.

The letter reads in part:

"This is a formal request to ask you to preserve any and all documents...and/or evidence related to Dr. Bao's claims and/or the Trayvon Martin Case."

Bao performed Trayvon Martin's autopsy after Zimmerman shot dead the 17-year-old on February 26, 2012.

During Zimmerman's trial, Bao's testimony stood out.

He changed his mind on important aspects of the case, such as how long Martin survived after he was shot, whether he could have moved afterward and if the marijuana in his system affected his judgment.

Bao's attorney, Willie E. Gary, said he plans to file a lawsuit for discrimination, job harassment and wrongful termination, the Miami Herald reported.