I'm far from a legal eagle, but I heard a former prosecutor talking about any time a grand jury is involved it raises some red flags, that they're easier to tamper with. I wish I had the link, I'm not one to claim this is true even, but it was a very interesting anecdote.
Edit found link: this is a podcast so I don't have timestamp, but one of my fav podcasts, and this was quite a bit different than what they normally put out
https://traffic.libsyn.com/secure/mattandshanessecret/MSSP_389_-_AUDIO.mp3?dest-id=446194