The US Department of Justice has announced an investigation into the shooting of an unarmed black teenager in Florida in February.
Trayvon Martin, 17, was killed by neighbourhood watch volunteer George Zimmerman, 28, while walking through a gated community in a suburb of Orlando.
Mr Zimmerman says he was acting in self-defence.
Rallies were held on Monday to demand his arrest, and an online petition has more than 500,000 signatories.
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 Tuesday at a Sanford church.
More than 500,000 people have signed a global online petition asking for Mr Zimmerman, a neighbourhood watch volunteer, to be prosecuted. Read more at the BBC...