While I’ve treated this as a story, "3melyZkng" looks like a Base64 encoded string or a randomly generated hash.
– A grainy, low-exposure photo of a basement floor with chalk lines. 3melyZkng.rar
– Twelve seconds of what sounded like a person breathing through a scuba mask, layered over a high-pitched rhythmic pulse. While I’ve treated this as a story, "3melyZkng"