My defendant favors using private browsing mode for a number of reasons including preventing friends from being able to access his personal accounts and to lower the risk of tracking and accidentally acquiring viruses.
Here are the Facebook logs from the past two weeks all using the same session token, demonstrating that your client is lying. And now when you try to explain that ok, maybe some information was deleted but that's only because it was embarrassing, and it wasn't evidence of any crime whatsoever, you'll have zero credibility...