The way I look at it; take the basic "crime", looking at porn on your works computer, now everyone here knows, that's gross misconduct your employer investigates and with the overview of it systems shouldn't be too difficult t o prove/disprove, plus most company's have a multitude of blocks to stop you accessing in the first place, and straight out the door.
So I ask
a) how was it originally discovered
b) once discovered, was it properly investigated
c) what was the outcome of any investigation; if proven and he didn't go, points to a cover-up and porky pies.
d) why was plod called in