Department of Justice opens investigation into case of black teenager killed by neighborhood watch captain

ORLANDO, Fla. –  The Department of Justice is launching an investigation into the shooting death of a black Florida teenager by a neighborhood watch captain last month.

In a statement released Monday, the DOJ said the investigation would be a joint operation between its Civil Rights Division, the U.S. Attorney's Office for the Middle District of Florida, and the FBI.

"The department will conduct a thorough and independent review of all of the evidence and take appropriate action at the conclusion of the investigation," the statement said.

The DOJ said it will also assist and cooperate with the state authorities on the investigation.

17-year-old Trayvon Martin was killed by 28-year-old George Zimmerman as he was walking home through Zimmerman's Sanford, Florida gated community last month. 

Zimmerman had called 911 to report Martin as a suspicious person, and has claimed he shot Martin, who was unarmed, in self-defense.

The department's announcement comes after Florida college students held a rally demanding for Zimmerman's arrest. They claimed Martin had done nothing to provoke the attack from Zimmerman, and that he was a victim of racial profiling.

"I don't think a man who exited his vehicle after the 911 dispatcher told him to stay inside the car can claim self-defense," Carl McPhail, a 28-year-old Barry University law school student, said at a rally in Sanford.

Zimmerman has not been charged in the case. Although police have described him as white, his family says he is Hispanic and not racist. 

Prosecutors may not be able to charge Zimmerman because of changes to state law in 2005. Under the old law, people could use deadly force in self-defense only if they had tried to run away or otherwise avoid the danger.

Under the new law, there is no duty to retreat and it gives a Floridian the right "to stand his or her ground and meet force with force, including deadly force," if he feels threatened.

"Prosecutors can have a hard time making a case if there is no one else around to contradict a person who claims self-defense," said David Hill, a criminal defense attorney in Orlando. 

So far, Sanford police have said there is no evidence to contradict Zimmerman's claims.

"If there is nobody around and you pull a gun, you just say, `Hey, I reasonably believed I was under imminent attack. Hey, sorry. Too bad. But you can't prosecute me,"' Hill said, somewhat tongue-in-cheek.

Gun control advocates said the case is emblematic of permissive gun laws in Florida, which was among the first states to allow residents to carry concealed weapons. Florida was the first state to pass a "Stand Your Ground" law, which has been dubbed a "Shoot First" law by gun control advocates.

Currently, about half of all U.S. states have similar laws, said Brian Malte, legislative director of the Brady Campaign, which describes itself as the nation's largest organization dedicated to the prevention of gun violence.

"It's coming to dangerous fruition," Malte said. "There are more states like Florida."

The "Stand Your Ground" law's legislative sponsor, Florida Rep. Dennis Baxley, said it wasn't written to give people the power to pursue and confront others.

"That's not what this legislation does," said Baxley, a Republican. "Unfortunately, every time there is an unfortunate incident involving a firearm, they think it's about this law, and it's not."

The Associated Press contributed to this report.