Suggested hashtag: #ShitBirdSchiff in addition to #ReleaseTheMemo
I FOIA'd the OIG investigation back in August to get info on progress (if you recall it totally dropped off the news cycle entirely for more than 8 months).
It was denied with a B7 exemption: law enforcement investigation materials.
Now, my understanding is that OIG investigations are not necessarily prima facie law enforcement, as they also cover things like ethics and waste.
My guess is the OIG is the source, but I'll also say not necessarily all of these are indictments – some may be sealed warrant applications, etc. They're simply sealed legal filings.
The grand juries themselves, in the cases of indictments, would be formed wherever there is a federal court in said jurisdictions. OIG could ask for a venue change in order to make this happen, as I understand it.