The Justice Department has opened an investigation into the shooting death of Trayvon Martin.

The agency said in a statement late Monday that it will perform an independent review of the evidence and take appropriate action.

History of Calling Law Enforcement

We now know the neighborhood watch volunteer who admitted to killing a teenager last month was calling law enforcement frequently, reporting men he thought were acting suspicious, all of whom were black.

You can listen to the non-emergency calls made by George Zimmerman by clicking the link to the right of this story.

  • “Dispatcher: Is he White, Black or Hispanic? Zimmerman: Black.”
  • “Dispatcher: Mr. Zimmerman can you describe the 2 individuals? Zimmerman: 2 African American males.”
  • “Dispatcher: And are they Black, White or Hispanic? Zimmerman: 2 Black males in their late teens.”

Officials say Zimmerman called law enforcement at least dozens of times, possibly even more. And in most of the newly released calls, Zimmerman talks about one or two, young black men, much like the man he says he killed in self-defense, 17-year-old Trayvon Martin.

Demonstrators Rally for Justice

The calls for justice in the case of an unarmed teenager shot and killed in Seminole County have spread across Central Florida and into the social media world.

Hundreds marched through the streets of Titusville on Sunday, demanding justice in the case of 17-year-old Trayvon Martin, who was killed in February by a neighborhood watch volunteer.

On Monday, people stood outside the Seminole County Courthouse, demanding the arrest of 28-year-old George Zimmerman.

So far, the neighborhood watch volunteer has not been criminally charged in Martin's death.

Dozens of community members and law students from Florida colleges held signs chanting “Arrest Zimmerman now.”

“By refusing to arrest George Zimmerman, law enforcement has empowered a citizen to take the life of a child with no consequence,” said FAMU Law Student Ese Ighedosa.

Zimmerman called 911 after seeing Martin, who was walking through the Twin Lakes subdivision, heading to his father's fiancee's home.

Zimmerman told operators there's been multiple break-ins recently, and Martin, who was wearing a hoodie, appeared suspicious.

“I'm just an angry member of the community, because I feel like any of us can go to the store in a hoodie and get shot. Apparently in Sanford you can do it and get away with it,” said protestor Tiffany Castro.

Monday's rally was organized by the members of the Black Law Students Association of FAMU College of Law, who are calling for Zimmerman's arrest.

They demanded to meet with the State Attorney’s Office Chief of Operations Pat Whitaker, who is now in charge of the case.

Whitaker obliged and they spoke about the evidence, including the 911 call Zimmerman made before the shooting.

“Are you chasing after him?” the operator asked.

“Yep,” Zimmerman said.

“Ok, we don't need you to do that,” the operator said.

Law students asked Whitaker why the man who initiated the confrontation isn't being charged.

“Pat Whitaker insinuated that there is more evidence outside the 911 tapes that is supporting the state attorney's decision to not file charges at this moment,” Ighedosa said. “We're asking for transparency. If there is evidence that is clear enough for you to not make an arrest we ask that you let the public know.”

In another 911 call, you can hear someone scream for help before the gunshot. But there's still debate whether that was Martin's voice, or Zimmerman's.

“(Whitaker) let us know that voice analysis would be done,” law student Jason Reed said.

Zimmerman said there was a fight and the shooting was self-defense. Sanford police agreed and gave the case to the State Attorney's Office without filing charges.

“When that question was asked whether Sanford PD did a fair and impartial investigation, Pat Whitaker would not use those words. He just said, ‘I'll say they did a reasonable job,’” Ighedosa said.

The State Attorney's Office is now faced with going over all the evidence. Whitaker has called in the FDLE to assist in the investigation. He said it could take weeks to determine whether Zimmerman will be charged with the killing.

If so, Whitaker said those charges could simply be manslaughter, not murder.

Besides talk of more rallies, even more fireworks are expected this week in the case.

The Florida Civil Rights Association is expected to request Monday that the state of Florida take away Zimmerman's concealed weapons permit.

On Tuesday, the NAACP plans a town hall meeting, and on Thursday, the Rev. Al Sharpton plans a rally in Sanford.

Sanford Mayor Jeff Triplett has met with local leaders, and has promised to do everything he personally can do to make sure the case of Trayvon Martin is handled fairly.

Triplett has also asked to meet with U.S. Attorney General Eric Holder this week.

What's keeping Zimmerman out of jail?

We spoke with Orlando-based Defense Attorney Shayan Elahi about the factors that may be keeping Zimmerman out of jail.

"I think I am very surprised by the fact that Sanford police would be so reckless in their behavior, not only if they were going to arrest Mr. Zimmerman,” Elahi said. “They needed to talk to the parents, they needed to explain to the community why this was not happening."

Elahi said all the Sanford Police Department needs to arrest Zimmerman for Martin’s death is probable cause. He said there is plenty of that in this case.

Zimmerman remains a free man, shielded from jail for several reasons.

Elahi said there are major holes with how police have handled the investigation thus far.

"What’s really disturbing, that they took the child's blood test, as Mr. Zimmerman thought that he was on drugs. But they did not test Mr. Zimmerman. One thing that’s crucial is that preserving the evidence. How will we ever know if Mr. Zimmerman was on drugs," said Elahi.

Zimmerman is claiming self-defense. Changes to Florida's "Stand Your Ground" law may also lend insight into why the neighborhood watch captain has not been arrested.

In 2005, that law extended the area from where you can defend yourself by using lethal force to well beyond your personal property or home.

Elahi said the amendment drew criticism from the get go, and this case is a perfect reason why it was the wrong decision.

"Even police officers said that they are very uncomfortable with this because it sends a wrong message, that people can use self-defense theory, basically a poster child for this case,” Elahi said.

However, that law only applies if the one doing the shooting feels threatened for his life.

Elahi said the 911 tapes from that night prove Zimmerman was chasing Martin, not the other way around.

"A lot of people in Central Florida and at this point the nation are saying, obviously Mr. Zimmerman was chasing this young man down," said Elahi.