Absent any written documentation ,
or a willing witness to offer testimony ,
it is all “hearsay”.
You cannot prosecute on a “Gut-hunch”
We don’t have to prosecute. We have to investigate. Even then we don’t have to prosecute but instead to form a select committee to consider articles of impeachment.
When you violate public trust and public official office duties the standards for action are much lower.
I think a select committee for each issue is in order in the House. One for White House abuse of IRS, one for the Libyian lies and abandonments to certain death and those related cover-ups, a third for Fast and Furious, another for NASA security investigations stopped, and I think one for whatever new thing pops up.
The dems love these — had them all the time when W was pres.