The last part of the note conveys fear. He wrote, “It almost seems like certain death to stay here.”

But the next morning he insisted on sending the fishing boat away, saying in the letter he had met someone in South Africa who went through a similar experience on a different island in the Andamans and won the trust of islanders only after being dropped off by a boat.

He seemed now to be contemplating the end, writing in the note, “Remember, the first one to heaven wins.”

The fishermen told the police the next morning that Mr. Chau swam to the island. They then went to the ocean to fish.

When they returned to North Sentinel a day later to check on him, they saw a group of islanders on the beach dragging Mr. Chau’s body with a rope.

All five fishermen have been arrested, along with two others, accused of helping lead Mr. Chau to his death.

“I am frustrated hearing John’s name,” said Naw Halen, the wife of one of the fishermen. “He has filled my family with sorrow for our whole life.”