He tried to speak to the tribespeople, who were small in stature and wore yellow paste on their bodies, in their own language. Some were friendly, others were not, according to Mr. Pathak, who cited a long note Mr. Chau gave the fishermen just before he set out in his kayak in case he did not come back.

Image John Allen Chau, an American from Washington state, was killed on the Indian island of North Sentinel. Credit... Sarah Prince/Associated Press

In it, he wrote that Jesus had bestowed him with the strength to go to the most forbidden places on Earth, police officials said.

His father, Patrick Chau, said Thursday that his Christian faith provided solace after hearing of his son’s death. He said he was particularly comforted by a biblical passage: “There’s time and seasons for everything under heaven.”

Missionary organizations said Mr. Chau died for the ultimate cause and friends called him a martyr.

“John was a gracious and sensitive ambassador of Jesus Christ,” said a statement from All Nations, an international Christian missionary group. “The privilege of sharing the gospel has often involved great cost. We pray that John’s sacrificial efforts will bear eternal fruit in due season.”

According to the fishermen who helped Mr. Chau, they motored for several hours from Port Blair to North Sentinel. Mr. Chau waited until the next morning, at daybreak, to try to get ashore. He put his kayak in the water less than half a mile out and paddled toward the island.

The fishermen said that tribesmen had shot arrows at him and that he had retreated. He apparently tried several more times to reach the island over the next two days, the police say, offering gifts such as a small soccer ball, fishing line and scissors. But on the morning of Nov. 17, the fishermen said they saw the islanders with his body.