The US Justice Department said on Tuesday it will not file civil rights charges against George Zimmerman, a Florida neighborhood watch volunteer who fatally shot unarmed black teenager Trayvon Martin in 2012.
The department said it had not found sufficient evidence that Zimmerman intentionally violated the civil rights of Martin, 17.
The announcement comes as the Justice Department also investigates Darren Wilson, a police officer who shot and killed unarmed black teenager Michael Brown in Ferguson, Missouri, in August.
Both incidents sparked nationwide outcry from civil rights advocates who have pressured the Obama administration to press charges against the two men for acting on racial bias.
Thursday will be the third anniversary of Martin's shooting.
"Though a comprehensive investigation found that the high standard for a federal hate crime prosecution cannot be met under the circumstances here, this young man's premature death necessitates that we continue the dialog and be unafraid of confronting the issues and tensions his passing brought to the surface," Attorney General Eric Holder said in a statement.
A source familiar with the investigation said it has been clear for some time that there would be no federal charges against Zimmerman. The Justice Department's civil rights division has been investigating for more than two years.
Zimmerman claimed he acted in self-defense when he fatally shot Martin in the chest during a confrontation in a neighborhood in Sanford, Florida, after following and stopping the teenager because he thought he was suspicious.
In 2013, he was acquitted of second-degree murder and manslaughter.
A spokesman for Martin's family earlier said they were meeting with Justice Department officials on Tuesday.
Zimmerman's attorney, Don West, did not immediately respond to a request for comment.