FOUND: Briefcase at Crambleside bus shelter, contents are different every time I check (Crambleside)

Found a brown leather briefcase at the Crambleside/4th bus shelter on Thursday. Nobody claimed it. I brought it home so it wouldn't get rained on.

Opened it Thursday night to look for ID. Contents: a Thermos, two pens, a manila folder with what looked like tax documents, and a sandwich (turkey, I think).

Opened it Friday morning to check the tax documents for a name. Contents: a set of screwdrivers, a children's book in a language I don't recognize, and a single rubber boot (left foot, women's size 8). No sandwich. No Thermos. No tax documents.

Opened it Saturday. I don't want to talk about what was in there Saturday. I closed it very quickly.

Opened it Sunday because I have no self-control. Contents: the Thermos again, the sandwich again (still fresh??), and a handwritten note that said "STOP OPENING THE BRIEFCASE." No signature.

I am going to open it again tonight. If this is yours PLEASE come get it. I can't stop checking. I've tried. I set an alarm this time.

Brown leather, brass clasps, initials "W.K." or possibly "M.K." depending on which day you look at it.