Zimmerman surrendered to authorities and is currently in custody. On Thursday's Today show, his new attorney, Mark O'Mara, said his client will enter a plea of not guilty.
In Florida, a charge of second-degree murder carries a maximum sentence of life in prison, according to CNN.
Lawyers for Zimmerman, 28, stepped down from the case Tuesday, saying Zimmerman had been uncommunicative and expressing concern for his emotional and physical well-being.
"As of the last couple days, he has not returned phone calls, text messages or emails," Craig Sonner, one of Zimmerman's former attorneys, said at a press conference Tuesday. "He's gone on his own. I'm not sure what he's doing or who he's talking to. I cannot go forward speaking to the public about George Zimmerman and this case as representing him because I've lost contact with him."
Describing Zimmerman as "emotionally crippled" by the scrutiny he's faced in the wake of the shooting, attorney Hal Uhrig said Tuesday that he and Sonner are concerned for their former client's mental and physical well-being. They also implied that he may have left Florida in the wake of media coverage about the case.
He also set up a website to collect donations without his lawyers' knowledge, they have said.
Zimmerman, who is Hispanic, maintains he was acting in self-defense when he shot Martin, 17, on Feb. 26 in Sanford, Fla. The teen was on his way home from a 7-Eleven, carrying a bottle of iced tea and a packet of Skittles.
The shooting has sparked a national debate about race and gun laws, with even President Obama speaking out about the incident.