A former federal prosecutor sends in this note.
May 9, 2017: CNN reports that grand jury subpoenas have been issued in Flynn investigation.
May 9, 2017: Trump fires Comey.
Did Trump find out about the subpoenas and continued investigation before the decision to fire Comey? This could be a key fact for Mueller’s team to determine. If Trump was telling Comey to let Flynn go and then he finds out that, rather than letting him go, subpoenas start flying, that would be compelling evidence of intent to obstruct. Mueller will have to dig into internal White House communications (emails, texts, meetings) about what Trump knew about the Flynn investigation, when he knew it, and what he was saying about it to those in his orbit. Given what he was saying to Comey, you would have to imagine that he was saying a lot more to his inner circle.