OK, lets try this again:

If the bent cop is investigated:
Cop will return Guilty
Bent Cop will return Innocent (or so you'd think)
Naive will get Innocent
Paranoid will get Guilty
Insane will get Innocent

2 Guilty, 2 innocent

Similarly if a good cop is investigated, we will get:
Cop will get innocent
Bent cop will get guilty (or maybe innocent, depends really)
Naive cop will get innocent
Paranoid will get guilty
Insane will get guilty.

So if Cop is investigated, he will get 3:1 guilty. If Naive is investigated, he will get 3:1 guilty, if Paranoid is investigated, he will get 2:2, if Insane is investigated, he gets 2:2.

Frustrating.