Republicans in the House withheld incriminating transcripts of interviews by Trump Jr and Roger Stone from the FBI/Muller. They will now be handed over to Muller's team by Democrats..
https://www.theguardian.com/us-news/...-investigation
Schiff said he was “trying to deconflict” with special counsel Mueller’s investigation because over the last two years the committee, under Republican leadership, had actively tried to make the special counsel’s work more difficult.
Schiff said he planned “as one of our first acts to make the transcripts of our witnesses fully available to special counsel for any purpose, including the bringing of perjury charges”