What I’ve done so far is to look at it two ways.
When I used the methods you described, I found that our MC is basically going through those methods. This is a Failure/Bad book (a noir), so even though she finds the evidence against this villain, it doesn’t solve her original goal. It actually makes things worse for her personal life, particularly her marriage (long story).
What I did was to go into the character tools in Dramatica, to see what traits fit the villain. Once I had a list (he’s quite complex), I looked at the list to see what mistakes he might make, particularly ones with paper trails.
Edited to add: I also looked at what others have already said about him so far in a negative sense (weaknesses), to see what if anything I might exploit.
So it’s a start. If I figure anything else out, I’ll let you know.