Well, that would be about a crime in IDAHO, not PA. And a Grand Jury in PA can't investigate a crime in IDAHO. The PA GJ can only investigate crimes in PA, and in that specific county. Not crimes in other parts of PA or crimes in ID. Now if DS were killed by a Ka-Bar knife in PA, and the parents testified that BK had the Ka-Bar knife in PA,
that information could be shared with ID, but that does not put the knife in ID, either.
The GJ seems to have been an investigatory one, and there are lots of posts above about that. There are also posts that LE says they have no evidence linking BK to the murder of DS.
www.law.cornell.edu