Nothing familiar... in fact, worryingly unfamiliar. These are not the voices that seng the merry nightly song. No indications on the butcher's identity, but perhaps touching base with Mingyu's players about the recent discovery of letters might... help you out, if characters agree some information sharing.

That said, if you give me a hint of what kind of things the folks in your crew might look at or do, I can list more findings, if any available.