Trayvon Martin's family asks feds to investigate

(CBS News) - The lawyer for Trayvon Martin's family tells CBS News they'll file a formal request with the Justice Department Monday, asking whether Florida prosecutors have been negligent by not charging a neighborhood watch volunteer who killed their son.

The Martin family wants to know why the Florida state attorney Norm Wolfinger allegedly overruled the police who wanted to arrest George Zimmerman on the night of the shooting.

Wolfinger stepped down from the case last month. Special prosecutor Angela Corey, Wofinger's replacement has been re-interviewing witnesses and examining evidence.

Complete coverage: The shooting of Trayvon Martin
Trayvon Martin shooting: What do we know?

The case has sparked questions nationwide about whether race played a role in the killing. Zimmerman insists he shot Martin in self-defense after the teen attacked him inside a gated community in Sanford, Fla..

But Martin's relatives, including his brother, do not accept that story. "It's just baffling how people they just take his word for it as if that's exactly what happened and there's no question about it," Jahvaris Fulton told CBS affiliate WFOR.

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A newly released emergency dispatch recording offers more details into the shooting. The tape shows a second ambulance called to the scene of the shooting was called off, bringing the severity of Zimmerman's injuries into question. "You can cancel second rescue. Second patient is not gunshot," according to the dispatch call.

On "Geraldo at Large" Sunday night, Martin's mother Sybrina Fulton said she's confident Zimmerman will end up behind bars. "I just truly believe that they're still investigating but things have leaked out and I believe he's going to be arrested very soon."

Protests over the shooting death of Martin moved to Miami Sunday, as thousands called for an arrest in the case. Five weeks after Martin was killed, his mother thanked a crowd in Miami, for demanding justice for her son's death.

Strangers like Mark Lumsden turned out by the thousands to show support. "I had to make an effort and come out with my friends because this just totally upsets me," Lumsden said.

Over the weekend, activists marched on the Sanford police department demanding Zimmerman be jailed.