A neighborhood watch volunteer charged with second degree murder in the shooting death of unarmed Florida teen Trayvon Martin appeared for the first time before a judge Thursday.

George Zimmerman acknowledged the charges before being led out in handcuffs.

He is expected to plead not guilty at his formal arraignment on May 29.

A special prosecutor announced the charges against Zimmerman on Wednesday.

He had already turned himself in and was being held at a Sanford police station.

Zimmerman's new attorney, Mike O'Mara, said his client will claim self-defense under Florida's "Stand Your Ground" law.

Martin, 17, walked around a gated Florida community on February 26, when he was shadowed by Zimmerman, who then shot the teen.

"It was a horrible intercession of two young men's lives, and it ended in tragedy. We have to figure out how it happened, why it happened, and who might be responsible for it," said O'Mara.

"We are seekers of the truth and seekers of justice. We looked at all of the evidence and applied the law; and based on our experience; we felt it was the proper case," said Assistant State Attorney Bernie de la Rionda.

After word of Wednesday's arrest, Martin's parents offered their thanks to the prosecutor, and the people who've helped them through the last 45 days.

"I just want to speak from my heart to your heart, because a heart has no color. It's not black, it's not white. It's red. And I want to say thank you from my heart to your heart," said Martin's mother, Sybrina Fulton.

"White, black, Hispanic, Latino we will continue to walk, we will march and march and march until the right thing is done," said Martin's father, Tracy Martin.

The second-degree murder charge carries a sentence of 25 years to life.