Enhanced video of George Zimmerman being led into a Florida police station appears to show possible injuries to the back of his head, lending credence to his claim he was in a struggle with Trayvon Martin when he shot the teen.

ABC News initially released video of Zimmerman that did not clearly show marks on his scalp, but had the video enhanced digitally and released a new clip on Monday. That clip appears to show a gash. Zimmerman's father claims his son was being beaten by the 17-year-old teen when he shot Martin in self-defense. Martin's supporters say Zimmerman shot the unarmed teen on Feb. 26 after racially profiling him and stalking the youth through his neighborhood.

Zimmerman's attorney, Craig Sonner, said Monday that his client would surrender to authorities if charged. Sonner told Reuters that his client is not hiding from authorities.

"There’s not going to be a manhunt or anything like that," Sonner told Reuters.

Also on Monday, Martin's parents asked federal officials investigating the teenager's shooting death to look further into the prosecutor who stepped down from the case and his role in deciding whether to press charges.

In a letter to U.S. Department of Justice officials, Tracy Martin and Sybrina Fulton allege that State Attorney Norm Wolfinger met with the Sanford police chief within hours of the teen's death and that together they overruled a detective's recommendation that Zimmerman be charged with manslaughter. The letter claims a lead investigator filed an affidavit stating that he didn't find Zimmerman's story credible.

Wolfinger called the allegations "lies" and said no meeting took place.

"I'm outraged by the outright lies contained in the letter," Wolfinger said in a statement. "I encourage the Justice Department to investigate and document that no such meeting or communication occurred."

Wolfinger recused himself from the case two weeks ago and a special prosecutor from Jacksonville is now investigating the shooting. Wolfinger said he wanted to avoid the appearance of a conflict of interest and to tone down the rhetoric in the case.

Martin's parents want to know why Wolfinger's office made the decision not to charge Zimmerman after the shooting. Zimmerman told police he was attacked and fired in self-defense. The U.S. Justice Department is already looking into the Sanford Police Department's handling of the case.

The Associated Press contributed to this report.