So from what I'm reading the findings of the Grand Jury don't have to be released to the public at all? Everyone will know the verdict obviously because it will go to trial or not, but no information is released unless the witness chooses to talk about their testimony and only their testimony, if they feel like it. So it's possible he won't go to trial and people will hear nothing, depending on what other agencies, Like the DoJ, decide to release of course. Only had a quick read of a long document btw, so I could be wrong.
Keep in mind also that cops tend to only testify when they won't get charged and the prosecutor is making no case at all.