Is it really his laptop? If so, why are you searching through it so much? Even though you're catching him in a lie, I think it's a bit invasive.

People need to set boundaries when it comes to computer "spying". When my wife uses my laptop for the Internet, she uses a different browser so she doesn't see my history...not that I'm looking at anything really bad, though I'm sure she wouldn't be pleased to find out that I've been Googling things like "suicidal thoughts" (not that I'm having any at the moment, but I do check such things).

I'm not trying to be confrontational, just offering some advice.