What did the second vistor do ? What was the cause of the captain's death ?

The day after Billy Bone's disturbing behavior, Jim observes a blind man wearing a tattered old cloak, tapping a stick, approaching the inn. Innocently, the man asks where he is but when Jim tells him and leads him to the entrance to the inn, the man cruelly grabs a hold of Jim's arm and threatens to break his arm if he does not take him directly to Billy Bones, introducing him as "Here's a friend for you, Bill." Billy Bones dies soon after the blind man leaves. This would probably be from his stroke and the stress of seeing the blind man.