Lionel Tate, who is serving a sentence of life in prison, claims he did not kill a 6-year-old Tiffany Eunick four years ago when he was pretending to be a wrestler but instead accidentally fell on her.
A partial transcript of an interview to be aired on ABC's 20/20 newsmagazine said Tate jumped from a spiral staircase onto Eunick, killing her.
"Lionel went upstairs to the bathroom. When he came down, like a 12-year-old, he bounded down the stairs, he jumped, and he landed on her," his attorney Richard Rosenbaum said.
Rosenbaum was asked how jumping on the little girl could cause 30 wounds, including a severed liver.
"Well, Lionel describes it as she jerked up like, like she'd been hit with a (defibrillator), and her head hit the ground again," Rosenbaum said. "Then I think he tried to move her and he might have bumped into something. But the liver laceration occurred when he jumped."
Tate, now 16, had said he had given the girl a bear hug. Prosecutors said he beat, kicked and stomped on her over a five-minute period.
He was convicted of first-degree murder two years ago and sentenced to life in prison.
Gov. Jeb Bush and the clemency board turned down his first application for clemency shortly after Tate began serving his sentence. Documents for a second attempt were filed in Tallahassee on Thursday.
Prosecutor Ken Padowitz obtained the guilty verdict in circuit court in Fort Lauderdale, Fla., but has long since insisted the sentence was too harsh for a crime committed by a 12-year-old.
"Any attempt to re-try the murder case in the court of public opinion is a distraction from the true issue -- that the sentence is too harsh and is not appropriate for a crime committed at the age of 12," Padowitz said Thursday.
After filing the petition for clemency, Rosenbaum argued at a hearing in circuit court in Tallahassee that Tate's prison disciplinary record should not be made public. The state will not release them because of his age, and The New York Times newspaper group has sued to get the records.
The issue was taken under advisement.
Tate told 20/20 he has been in trouble at the juvenile facility where he is being held.
"Mostly talking too much or talking loud ... during inappropriate times or maybe horse playing or something," Tate said.
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