Something to consider about this development. A special prosecutor can in some ways help Trump from what was a shitstorm of public controversy, particularly something that stands to be truly damning to him; Comey publicly testifying. Which, if he confirmed the memos publicly, would have the ex FBI head fired by Trump, publicly branding Trump as a liar. That doesn't seem like that big a deal to anyone with a pair of ears and eyes, Trump is a brazen liar who constantly spews fallacies. But the impact of that sort of public testimony would be very damaging to Trump, as well as whatever other revelations Comey could bring forward.
This Graham fellow is saying this is now a criminal investigation :
https://www.washingtonpost.com/vide...a10d5a-3bff-11e7-a59b-26e0451a96fd_video.html
If he is correct a criminal investigation, means as he states, that those who are potentially going to face charges have a right to not self-incriminate. It also means someone like Comey who could be used as a witness, may not be wanted to testify publicly because of that.
So this may help Trump in terms of the constant bad publicity, particularly in that it insulates him, if Comey does not now testify publicly, from the PR disaster of Comey's testimony putting Trump on record as a liar. As well, they may now deflect each and every question by saying there is an ongoing criminal investigation and they don't want to comment. Another thing, is if this prosecutor is focused on criminal activity, it may allow the focus on any other activity that is not criminal but grossly unethical, to slip to the wayside.
This is an interesting read and lends some thought to how he could possibly benefit from this:
https://www.theatlantic.com/politics/archive/2017/05/a-special-prosecutor-is-not-the-answer/526662/