MIAMI — George Zimmerman, a neighborhood watch volunteer accused of killing an unarmed black teenager earlier this year, on Tuesday waived his right to a speedy trial and asked for more time to prepare his case, according to court documents.

Zimmerman's lawyer presented petitions in the Florida court for the 28-year-old, who faces second degree murder charges after being freed on bail on April 23.

The motion showed the state of Florida did not oppose the request. The law allows people accused of serious crimes to be tried within 175 days, but that time frame can be waived to allow legal teams to prepare their defense.

Zimmerman, 28, has pleaded not guilty to the charges arising from the shooting of Martin, 17, on February 26 as he crossed a gated community in the Florida town of Sanford on his way home from buying sweets at a local shop.

The case has attracted national attention, including protests led by civil rights leaders, because police initially accepted Zimmerman's claim that he shot Martin in self-defense.

They refused to arrest him until a special prosecutor finally brought second degree murder charges against him April 11.

He did not appear in court Tuesday, and has been out of the public eye since being freed on bail last month.