George Zimmerman made his first court appearance Thursday entering a not guilty plea in the shooting death of Trayvon Martin, 17.
In his first appearance, Zimmerman, 28, seemed thinner than he appeared in photographs previously made public. He said only two words -- "Yes, sir," -- during the hearing, which lasted for less than two minutes.
READ: Probable Cause Affidavit
READ: Zimmerman charge information
His attorney, Mark O'Mara, entered a formal plea of not guilty to the second-degree murder charge.
Second-degree murder was a more serious charge than Zimmerman expected, O'Mara said. It indicates that the prosecutors have evidence that they believe shows Zimmerman shot Martin, who was unarmed, in a more aggressive stance than self-defense.
"Does this mean that you feel there's evidence to show that George Zimmerman was the aggressor in this case?" Local 10's Glenna Milberg asked prosecutor Bernie de la Rionda.
"It is our obligation under the law to only file charges we can prove. Second-degree murder, we felt, is the appropriate charge, and that's why it was filed," de la Rionda said.
LIST: Zimmerman's jail purchases RELATED: Martin case Q and A
While prosecutors say little, the court documents they filed to show a judge probable cause for the arrest indicated that they give weight to evidence already made public. That includes a 911 recording that indicates that Zimmerman ignored a police dispatcher's advice not to follow Martin through his neighborhood on Feb. 26, the night of the shooting. It also includes the version of events told by Martin's friend, with whom he was talking on the phone at the time of the confrontation.
"I liken it to a picture that you have as puzzle pieces, and you throw out two or three or four pieces, and you cannot get a picture of it. And the frustration that happens is you see it one way, you see it another way. There's something missing, and somebody's not answering the next question. It's really supposed to happen in the courtroom," O'Mara said.
O'Mara asked everyone not to rush to judgment.
"Obviously, it was a horrible intersection 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 Zimmerman's attorney, Mark O'Mara.
The judge agreed to seal the case, granting Zimmerman's request to keep more details from public consumption. That was perhaps one reason his attorney did not request a hearing to try to get Zimmerman bond. He would have to bring more evidence before a judge in a bond hearing, and that would put much of the case in the public arena.