George Zimmerman, who shot dead unarmed black teenager Trayvon Martin in 2012, is suing his family, their attorney, the US state and others for around $100m (£77m).
The neighbourhood watch volunteer was cleared of the 17-year-old's murder in one of Florida's most-high profile criminal cases.
US law allowed him to say he shot Trayvon in self-defence, but the teenager's family and friends always insisted it was murder.
The lawsuit claims the Martin family and lawyers used a fake witness against George Zimmerman.
"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 lawsuit accuses Trayvon's parents and the family's lawyer Benjamin Crump of forcing Brittany Diamond Eugene, 16, who was reportedly the teen's girlfriend, to make a recorded statement that implicated George Zimmerman as the person who started the row with Trayvon.
Brittany was on the phone with the 17-year-old moments before it happened, the suit said.
It also alleges that Brittany's half-sister, Rachel Jeantel, pretended to be Brittany when she was interviewed by prosecutors and provided false statements to incriminate George Zimmerman based on coaching from others in court during his trial.
Benjamin Crump said in a statement, on behalf of himself and the Martin family, that he has confidence that the "unfounded and reckless" lawsuit will be revealed as "another failed attempt to defend the indefensible and a shameless attempt to profit off the lives and grief of others."
Trayvon's uncle, Ronald Fulton, 56, claimed the lawsuit was no more than a publicity stunt to promote a forthcoming documentary titled the "Trayvon Hoax" that claims Rachel Jeantel was an impostor.
What happened in 2012?
While serving as a neighbourhood watch volunteer in a gated community in Sanford, Florida in February that year, George Zimmerman spotted Trayvon Martin.
He was wearing a hoodie and had been to the shop to buy some Skittles and a soft drink.
Believing the teenager was up to no good, after a spate of robberies in the area, he tackled him.
Nobody witnessed what happened between them but a neighbour's call to the emergency services picked up cries for help and the fatal gunshot.
George Zimmerman's lawyer always said he was viciously assaulted by Trayvon Martin.
Gun laws in the US allow those who own firearms to shoot somebody if they feel they're in danger of being killed or seriously injured.
Because of this, Florida police didn't arrest George Zimmerman for six weeks after the shooting, provoking mass rallies in Florida and throughout the US.
George Zimmerman has always claimed he acted in self-defence.
The killing was instrumental in sparking the Black Lives Matter social movement.
It began after an activist in California named Alicia Garza wrote a post on Facebook. "Black people. I love you. I love us," she wrote. "Our lives matter."
She was angry that George Zimmerman had been cleared of the murder of Trayvon Martin.
She and two others started using the phrase "Black Lives Matter" as a hashtag online.
Benjamin Crump, the Martin family lawyer, said at the time: "Trayvon Martin will forever remain in the annals of history... as a symbol for the fight for equal justice for all."
In May 2016, George Zimmerman sold the gun that killed Trayvon Martin for $250,000 (£172,000) by auction.
Critics said he was seeking to profit from the killing.
Gun rights advocates said he was exercising his legal rights under US law.