George Zimmerman's lawyer said the biggest challenge is fighting against the "social pressures" surrounding the racially charged case and wished the jury was "more diverse."

Six women -- five white and one minority of Hispanic descent -- were chosen to serve on the jury.

"My concern from day one is that this is a very simple straightforward self-defense case, yet it's been turned into what one of the people has said is the greatest civil rights trial of the century," Mark O'Mara told "Nightline" anchor Dan Abrams. "It's absurd. This is still ... just a 'stand your ground' self-defense case."

Zimmerman, 29, is charged with second degree murder. He maintains he shot Trayvon Martin, 17, in self defense after the unarmed teenager attacked him in a gated Sanford, Fla., community on Feb. 26, 2012.

The killing inflamed racial tensions in the town as well across the country when police declined to press charges. Zimmerman, is white and Hispanic, while Martin is black.

Zimmerman was arrested two months later when a special prosecutor brought charges against him.

The racial overtones surrounding the case focused attention on the make-up of the jury.

"I would like to have had a more diverse jury only so that those people who want to complain would have less of a reason to complain," O'Mara said.

Without any black jurors on the panel, one of O'Mara's biggest concerns is how the black community will respond to the outcome of the trial.

"My biggest challenge is the way people are going to react to [the verdict] so I think that's a great concern," O'Mara said. "[But] we have a good jury and people have said that they will trust the verdict as long as it is a fair trial. They are getting a fair trial."

Catch up on all the details from the George Zimmerman murder trial.

Despite the fact the jury is sequestered, O'Mara said he was still "very concerned" they might hear information about the case from the outside.

"With the type of pressure that's been on this case and the type of publicity, I'm very concerned that any little thing that gets to this jury could affect them," he said.

At the heart of the trial, the jury will have to decide who started the altercation -- Zimmerman or Martin -- to see if Zimmerman's self-defense claim holds up. On Monday, the Florida court heard Zimmerman's voice for the first time when police audio recordings and a tape of his call to the police dispatcher were played for the jury. Jurors listened as Zimmerman explained in Sanford police recordings how he came to shoot the teenager.

"He was on top of my ... I shot him, and I didn't think I hit him because he sat up and said, 'Oh gosh you me, you got it, you got me, you got it," Zimmerman told lead investigator Chris Serino during a video re-enactment.

As for putting his client on the stand, O'Mara implied to "Nightline" that seemed unlikely.

"I hate to say that I made that decision, but I like the way the evidence is going so far," he said.