Black leather briefcase found near downtown Billings

I found a black leather briefcase with a brass latch this afternoon around 3:15pm near the main entrance of the Northern Hotel on 3rd Ave North in downtown Billings, Eastern Montana. It's a Samsonite-style case, about 15 inches wide and 11 inches tall, with a couple of scuffs on the bottom edge and a frayed handle. Inside there's a red notebook, a small blue USB drive labeled 'K.M.', and a faded travel itinerary. If this belongs to someone, tell me a distinguishing detail like the notebook cover color or the USB label, and I’ll arrange a safe handoff.