(CNN) -- An audio expert who analyzed screams on a 911 call recording during a struggle between George Zimmerman, a neighborhood watch volunteer, and Trayvon Martin, an unarmed teenager, said Monday that he doubts the screams came from Zimmerman.
Zimmerman has said he shot Martin to death in self defense, after the young man attacked him. He said immediately after the confrontation that he had yelled for help but that no one helped him, a police report says.
Ed Primeau, an audio expert with about 30 years experience, analyzed the 911 call.
"I would put my reputation on the line and say this is not George Zimmerman screaming," he told CNN on Monday morning.
The Orlando Sentinel first reported that he and another audio analyst who reached the same conclusion.
Martin's parents, meanwhile, will ask the U.S. Justice Department on Monday to review a Florida prosecutor's interactions with police investigating the teen's shooting death, a lawyer for the family said.
The Justice Department launched an investigation into Martin's death on March 19, but the family is now asking it to look for possible interference by State Attorney Norm Wolfinger's office with a Sanford, Florida, police detective, attorney Ben Crump said.
Martin, 17, was fatally shot by neighborhood watch volunteer Zimmerman, 28, after Zimmerman called police to report him as a "suspicious" person on the evening of February 26.
A police report filed hours after the shooting lists manslaughter under the offenses section. But police have cited Florida's "stand your ground" law, which allows people to use deadly force anywhere they feel a reasonable threat of death or serious injury, for not immediately arresting Zimmerman.
ABC News has reported that the lead homicide investigator, Chris Serino, filed an affidavit pushing for charges the night of the killing, but was overruled by the state attorney's office.
"It certainly confirmed all of my thoughts that this investigation had been botched from the beginning and that people other than me knew that there was supposed to be an arrest made," Martin's father, Tracy, told CNN after the ABC News report.
Zimmerman said he killed Martin in self-defense after the teen punched him and slammed his head on the sidewalk, according to an Orlando Sentinel report that was later confirmed by Sanford police.
Zimmerman's brother said medical records will prove that his brother was attacked and his nose was broken by Martin before he fatally shot the teen.
Martin's family and legal experts have questioned the Zimmerman family version after the recent release of surveillance videos from the Sanford police headquarters the night of the incident.
It shows Zimmerman, his hands cuffed, exiting a patrol car and being led into the police station. First broadcast Wednesday by ABCNews.com, the video does not provide close-ups, but also does not show clear signs of injuries on Zimmerman.
"We now have pictures of Mr. Zimmerman walking into the police station, and you see no injuries that would have come from abrasions on a sidewalk," said Lou Palumbo, a retired police officer who owns a private security firm.
"Anyone who's seen a broken nose is aware of the fact that the blood spurts. That leads to a lot of bleeding. You would have expected to see blood on the front of George Zimmerman's shirt collar. Blood -- you know, in many more places," said Marcia Clark, the former prosecutor in the O.J. Simpson trial.
Robert Zimmerman Jr. said his brother was treated at the scene before he was taken to police headquarters, and said it appeared to him that the surveillance tape shows that his brother had injuries.
Authorities have said Zimmerman was not immediately charged because there were no grounds, at the outset, to disprove his account that he'd acted to protect himself.
Martin's family and supporters say Zimmerman, who is Hispanic, racially profiled the teen, who was black, and ignored a police dispatcher's directive not to follow him.
Martin was unarmed, carrying a bag of Skittles candy and iced tea at the time of his death.
The killing sparked nationwide protests, including rallies Sunday in Indianapolis and Miami, where civil rights leaders and the slain teenager's parents were among those repeating their call to have the teenager's killer arrested.
The Sanford Police Department has come under scrutiny for its actions following the shooting, and protesters renewed their call for the firing of police Chief Bill Lee, who stepped aside temporarily last month amid criticism.
Wolfinger has also stepped aside.
Florida Gov. Rick Scott appointed a special investigator, Angela Corey, to decide if Zimmerman should be charged, cleared or if the case should be sent to the grand jury.
-- CNN's Anderson Cooper and Vivian Kuo contributed to this report.
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