The Flying Banjoman

We found the battered boat adrift off the coast of Nantucket.
Ragged body parts all over the deck, eventually we accounted for all the passengers, minus the pieces the seagulls dragged off.
Right there, jammed in the wheel, was a blood-soaked banjo.
“The uneasy spirit still roams the fog,” muttered the old harbormaster.
He reaches for the banjo and throws it back in the water.
“That’s evidence!” I shouted.
The harbormaster gave me a stare that drilled right into my bones.
“That’s what the last detective tried to tell me,” he said, and he pointed to… a severed lawman’s head.