Zimmerman's lawsuit, filed Wednesday, said a trial witness pretended to be the last person to talk to Martin by phone before he was killed when the witness was actually the half-sister of the caller.
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According to the lawsuit, Brittany Diamond Eugene didn't want to testify that she had been talking to Martin before he was killed. So her half-sister, Rachel Jeantel, pretended that she was talking to the teen before he was fatally shot. Jeantel ended up testifying at Zimmerman's 2013 trial in Sanford, Florida.
Martin was killed during a struggle with Zimmerman, who was a Neighborhood Watch volunteer.
Martin was black. Zimmerman's father is white and his mother is Hispanic. Zimmerman's trial raised questions about race and Florida's "stand your ground" self-defense law which allows people to use force without retreating if they feel threatened.
In a statement on Wednesday, Martin family attorney Benjamin Crump called the allegations "unfounded and reckless."
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"This plaintiff continues to display a callous disregard for everyone but himself, re-victimizing individuals whose lives were shattered by his own misguided actions. He 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's statement said. "This tale defies all logic, and it's time to close the door on these baseless imaginings."
Zimmerman's lawyer in the lawsuit, Larry Klayman, was planning a news conference in South Florida on Thursday to discuss the complaint. The lawsuit seeks $100 million, alleging malicious prosecution and conspiracy.
Klayman is a conservative activist who founded the watchdog group, Judicial Watch.
Last July, an ethics committee of the bar in the District of Columbia recommended that Klayman's law license be suspended for more than two years.