Florida special prosecutor Angela Corey plans to announce as early as Wednesday afternoon that she is charging neighborhood watch volunteer George Zimmerman in the shooting of Trayvon Martin, according to a law enforcement official close to the investigation.

It was not immediately clear what charge Zimmerman will face.

Martin, 17 and unarmed, was shot and killed Feb. 26 by Zimmerman, who said he was acting in self-defense. Police in Sanford, Fla., where the shooting took place, did not charge Zimmerman, citing the state’s “stand your ground” law.

Corey told reporters Tuesday night that she would hold a news conference about the case within 72 hours. A news release from her office said the event will be held in Sanford or Jacksonville, Fla.