The US Department of Justice has announced an investigation into the shooting of an unarmed black teenager in Florida.
Trayvon Martin, 17, was shot dead by George Zimmerman, 28, while Martin was walking through a gated community in a suburb of Orlando last month.
Mr Zimmerman says he acted in self-defence.
The case has caused controversy in the US. Earlier on Monday rallies were held to demand Mr Zimmerman's arrest.
Students protested in front of a court building in Sanford, the community where the shooting happened, and on the campus of Florida A&M University in Tallahassee.
Civil rights leader Al Sharpton plans a rally on Thursday at a Sanford church.
More than 480,000 people have also signed a global online petition asking for Mr Zimmerman, a neighbourhood watch volunteer, to be prosecuted.
The justice department said in a statement that it would "conduct a thorough and independent review of all of the evidence" before taking "appropriate action".
The FBI and a federal prosecutor in Florida will also assist in the investigation.
Mr Zimmerman, acting as a neighbourhood watch volunteer, had called police several times in the months before the shooting to report incidents.
Mr Zimmerman called police on 26 February, reporting there had been break-ins in the community, and that there was "a real suspicious guy" who "looks like he's up to no good".
When he said he was following the person he had identified as suspicious, the dispatcher said: "We don't need you to do that."
The release of emergency calls recordings, including two from neighbours during which screams and shots can be heard, had fuelled demands for a federal investigation.
The case has focused attention on a 2005 state law which allows deadly force if a person believes their life is in danger.