What would have been Warwick's crime?

Even if the polaroid Ben received in the mail, of Warwick and John together on Warwick's couch, proved to be genuine (which, as we know, it was), what crime would Warwick be charged with? What's illegal?

Obviously, Warwick's integrity and morals would be compromised if proven he knowingly had a wanted criminal over to his house, and took no legal action - since he is a police lieutenant in, presumably, the LAPD.

But, if anything else, since I don't think there was a time stamp on the polaroid, Warwick could just claim "Yes, I know John Taylor, and yes I had him over to my house, but before he committed the bank robbery and became a criminal. In other words, at the time I had John over, he was not wanted by the police, and as far as I know, a law-abiding citizen."

I mean, it would be no different then having a friend over, which we all have done, or going to a friend's house.

I guess, after John robbed the bank, and his identity was exposed, it would have been relevant that Warwick mention to his colleagues that he knows John, personally. But, who knows, if you were in Warwick's shoes, you might feel a bit embarrassed or ashamed, even, admitting you had John over to your house at one point.

Anyway, my point is, even if and when the polaroid is proven to be authentic, then what? What crime do they charge Warwick with?

Thanks so much for reading and I'd love to hear your guys' thoughts.

Take care.

On a side note, I always thought it was funny how after Warwick proudly tells John "I may be many things, John, but one thing I'm not, is a liar," he then lies through his teeth when he tells Ben he's never met John Taylor.