Civil rights leaders in the US have demanded the arrest of a neighbourhood watch helper who went free after shooting dead an unarmed black teenager.
The FBI is now investigating the incident in Florida, following a public outcry.
And at a public meeting in the town of Sanford, where 17-year-old Trayvon Martin was shot last month, officials from the American Civil Liberties Union, the National Association for the Advancement of Coloured People and the Nation of Islam urged residents to remain calm but demand that the shooter, George Zimmerman, be arrested.
Mr Zimmerman has not been charged in the February 26 shooting and has claimed that he shot Martin in self-defence after Martin, who was returning to a gated community after buying sweets at a convenience store, allegedly attacked him.
“I stand here as a son, father, uncle who is tired of being scared for our boys,” said Benjamin Jealous, national president of the NAACP. “I’m tired of telling our young men how they can’t dress, where they can’t go and how they can’t behave.”
The case has ignited a furore against the police in the Orlando suburb, prompting rallies and a protest in governor Rick Scott’s office.
The US Justice Department’s Civil Rights Division said it is sending its community relations service this week to Sanford to “address tension in the community.”
An online petition urging local authorities to prosecute Mr Zimmerman has drawn more than 700,000 signatures.
The federal agency has opened a civil rights probe into the shooting, and Seminole County State Attorney Norm Wolfinger said a grand jury will meet April 10 to consider evidence in the case.
“We are pleased the Department of Justice has heeded our calls and agreed to investigate this outrageous case,” Mr Jealous said.
“The rules of justice in this nation have failed when an innocent teenage boy can be shot to death by a vigilante and no arrest is made for weeks.”
A lawyer for Mr Martin’s family revealed the teenager told his girlfriend on his phone just moments before he was killed that he was being followed.
“’Oh he’s right behind me, he’s right behind me again,”’ he told her. Benjamin Crump said.
The girl later heard him say: “Why are you following me?” Another man asked: “What are you doing around here?”’
After Mr Martin encountered Mr Zimmerman, the girl thought she heard a scuffle “because his voice changes like something interrupted his speech,” lawyer Benjamin Crump said. The phone call ended before the girl heard gunshots.
Police arrived to find Mr Martin lying face-down.
Police said Mr Zimmerman, who was found bleeding from his nose and the back of his head, told them he yelled for help before shooting Mr Martin.
Mr Zimmerman was handcuffed after police arrived and taken into custody for questioning but was released by police without being charged.