Nobody can say for sure if he did it knowingly or not, and this isn't the point. One thing is when you try to hide the evidence (i.e. it can be proved that you

Nobody can say for sure if he did it knowingly or not, and this isn't the point. One thing is when you try to hide the evidence (i.e. it can be proved that you lied about it), but you fail to. The other thing is when there's no evidence. You cannot charge man with anything if there's no evidence of crime, but you "think" he destroyed it on purpose (prior to investigation). Maybe he deletes browser history on the daily basis. It's OK. There's nothing wrong with it. Shouldn't be. No matter how "suspicious" it seems to you, your suspicions don't matter.