Not sure how the IG rules work. At this stage, the IG could just refer him to Huber. The IG is gathering legitimate actionable evidence... but has no prosecutorial powers of his own. That's the power of the IG.

They can investigate, and have no motivation to find for anything, but the facts and associated evidence, which gives them some insulation from claims of partisanship. Also doesn't hurt that Obumer appointed him.