NBC just broke the news:

The special prosecutor in the Trayvon Martin case will announce criminal charges against George Zimmerman about 6 p.m. ET Wednesday, a law enforcement official told NBC News.

The nature of the charges weren’t immediately known, the official told NBC News Justice Department correspondent Pete Williams, speaking on condition of anonymity. But because Angela Corey, the special prosecutor appointed by Florida Gov. Rick Scott to re-examine the case, previously announced that she wouldn’t take the case to a grand jury, first-degree murder is not an option.