The OIG only reports facts. It will be up Rip Can Sessions to reach the likely conclusion that (1) Hillary and her cabal at State violated the espionage act, that (2) Hillary and her cabal obstructed justice, (3) key DOJ and FBI officials conspired to protect Hillary and her cabal from being prosecuted.
After which he would have no choice but to launch a full criminal investigation which is perhaps already underway by US Attorney Huber.
The IG is required to report any crimes he uncovers as he conducts his investigation. So Horowitz hasn’t been sitting on them, waiting to reveal them to prosecutors only when his report is finished.
Someone has been receiving this information. And if not Huber it’s someone just like him.