George Zimmerman, who shot and killed Trayvon Martin in Florida in 2012, is suing the teenager's family, their attorney, the US state and others for more than $100 million, his lawyer said on Wednesday.
Zimmerman said he shot Martin - an African American - in self-defence, but the teen's family and friends insisted it was a murder driven by racism.
While serving as a neighborhood watch volunteer in a gated community in Florida in February 2012, Zimmerman fatally shot high school student Martin as he was walking home with iced tea and candy.
Zimmerman insisted he had been following the teenager on suspicion he was involved in robbery, and that he shot him in an act of self-defence.
The lawsuit claims that "that the prosecution's key witness in his 2013 murder trial ... was an imposter" who "provided false statements to incriminate Zimmerman based on coaching from others," his lawyer Larry Klayman said in a statement.
The statement continued: "Zimmerman, who faced a life sentence had he been wrongly convicted, based on the alleged false evidence, is suing for damages in excess of $100 million"
Ben Crump, the Martin family's lawyer and one of those named in the lawsuit, slammed it as "unfounded and reckless," and said that it was "a shameless attempt to profit off the lives and grief of others."
Zimmerman "would have us believe that he is the innocent victim of a deep conspiracy, despite the complete lack of any credible evidence to support his outlandish claims," Crump said in a statement of his own.
"This tale defies all logic, and it's time to close the door on these baseless imaginings," he added.
Zimmerman's trial and subsequent acquittal exposed deep racial divides in US society, in a case that sparked nationwide protests.