"Yeah, if you're looking for someone, it's better to put their full name?" Just saying. It's obvious as hell to Hickey. Just putting down initials makes him think that Lester's trying to hide something—probably the full name of JD? What, is this guy a murderer or something? Why would he hide the full name?

It's curious. And Hickey kind of wants answers.

"I know a JD myself. John Diggle, ship's cook. It's probably not your JD, but how'm I supposed to know that if I'm just looking at the note?"