In the Bloomberg News story today about Robert Mueller's subpoenas of Paul Manafort's bank records is this little tidbit:
...Manafort had alerted authorities to a controversial meeting on June 9, 2016, involving Trump’s son Donald Jr., other campaign representatives and a Russian lawyer promising damaging information on Hillary Clinton, according to people familiar with the matter.
So it was Manafort who dragged them into it. Which means he's cooperating -- to an extent. Clearly, yesterday's no-knock warrant at Manafort's home indicates they want him to cooperate just a teensy bit more, or they don't trust everything he tells them and they're looking to turn up the heat.
Here's another little tidbit from the story:
Part of the reason Manafort is getting intense early scrutiny is that Mueller is drawing on investigations that were well underway, including one by federal prosecutors in Manhattan, when he was appointed in May.
This might be the first official confirmation that Mueller's and NY Attorney General Eric Scheiderman's investigations are overlapping, and that they are sharing some resources.