User blog comment:AltertheSilverBird/Total Drama: Danganronpa Chapter 5: Class Trial/@comment-25474566-20160505174241

Well...at first I thought that Lightning was the killer...now meh, I don't think so. He's connected with the crime but he isn't the killer (at least, I hope). I guess that Beth's killer is Jo, for my personal opinion. Lightning sent the letter to Jo. And don't forget this:

Gwen: Well that person would also be Beth's killer.

Lightning: Are you sha-serious!? How can that TRAITOR be the killer!?

So yeah, Jo is Beth's killer and Captain Modesty AKA Sha-Lightning sent the letter to her.