too many cooks
There are four concurrent federal probes into Russian meddling in the 2016 election and alleged collusion by President Trump or members of his campaign, and investigatory cooperation isn't going so well, thanks to poor communication and complex information distribution rules. Three congressional committees are on the case, as well as Special Counsel Robert Mueller, and CNN reports the parallel inquiries are struggling to share findings and access to key witnesses.
For example, the Mueller team approached the Senate Intelligence Committee to request the transcript of closed-door testimony from former Trump campaign chair Paul Manafort. The committee has yet to hand over the document, because Manafort's lawyers say they have not authorized the transfer, while Mueller's attorneys say they were previously granted access.
Meanwhile, Mueller's team has access to a letter Trump drafted before firing former FBI Director James Comey, a memo that reportedly explains his rationale for the ouster in illuminating detail. The House Intelligence Committee wants a copy, but will have to go through the White House, likely with a subpoena, instead of obtaining it directly from Mueller.
Then there are the personal memos Comey wrote to chronicle his interactions with Trump before he was fired. Lawmakers on the third investigating committee, the Senate Judiciary Committee, have been permitted to read the memos, but not to copy, take notes, or share them with the other three probes.