Most cases yes. Unsure of how they operate in DC.
GJ (local cases) Prosecutor comes into the room with a stack of file folders. Opens each one and talks thru the offenses and then brings in witnesses for the GJ to hear from. GJ can ask questions of both witnesses and prosecutor. Prosecutor leaves. GJ decides if there is enough evidence to move to court (indict) Its a very low bar.
We kick out only one case that was presented .