O'Mara replaces Craig Sonner and Hal Uhrig, the two lawyers who had been giving legal advice to Zimmerman.

CNN: George Zimmerman charged, hearing expected Thursday

Zimmerman's attorney, Hal Uhrig, told CNN that he was "not surprised" that Corey wouldn't present a case to a grand jury.

CNN: Zimmerman speaks, raises funds on new website

"I'm not sure when she came to that conclusion, " said attorney Hal Uhrig, noting that when news of the shooting first broke, pictures of Martin as a 12-year-old were the first to circulate.

CNN: STORY HIGHLIGHTS