A police booking photograph of George Zimmerman, taken after he was brought into custody on April 11 in Florida. (Seminole County Sheriff's Office/AFP/GETTY IMAGES)

George Zimmerman, the neighborhood watch volunteer who fatally shot Trayvon Martin last month, made his first appearance in a Florida court today.

During his brief appearance Zimmerman, looking thin and worn, said nothing.

The judge said the next court hearing will be May 29 at 1:30 p.m. ET and agreed with attorneys to seal the case records.

Zimmerman is charged with murder in the second degree for shooting Martin, who was unarmed.

Under Florida law, second-degree murder refers to a killing that is not premeditated but is carried out with “a depraved mind regardless of human life.” 

Zimmerman’s lawyer Mark O'Mara said his client will plead not guilty.

On NBC’s Today Show, O'Mara said Zimmerman is “concerned about getting a fair trial.”

But criminal justice lawyers say the Florida special prosecutor assigned to the case, Angela Corey, may have a tough time persuading a jury to convict Zimmerman on the charge.

Earlier on Thursday, Trayvon Martin’s mother Sybrina Fulton told the Today show that she believed her son’s killing was an accident.

She later backpedaled on her statement on MSNBC-TV, saying, “George Zimmerman stalked my son and murdered him in cold blood.”