Mark O'Mara now representing George Zimmerman

ORLANDO, Fla. – Attorney Mark O'Mara, who was a legal expert for WKMG-TV in Orlando during in the Casey Anthony murder trial and the ongoing Trayvon Martin death investigation is now representing George Zimmerman, the neighborhood watchman who shot and killed the teen in Sanford.

Zimmerman was charged Wednesday with second-degree murder in the shooting death of Martin.

State Attorney Angela Corey -- appointed special prosecutor in the case announced Wednesday afternoon that Zimmerman was charged with second-degree murder and has turned himself in.

Zimmerman's former attorney Craig Sonner and Hal Uhrig announced Tuesday they were stepping down from the case because they had no contact with Zimmerman since Sunday.