NEW DELHI — John Allen Chau had to know that what he was about to do was extremely dangerous.
Mr. Chau, thought to be in his 20s, was floating in a kayak off a remote island in the Andaman Sea. He was about to set foot on one of the most sealed-off parts of India, an island inhabited by a small, highly enigmatic tribe whose members have killed outsiders for simply stepping on their shore.
Fishermen warned him not to go. Few outsiders had ever been there. And Indian government regulations clearly prohibited any interaction with people on the island, called North Sentinel.
But Mr. Chau didn’t listen. Instead, he pushed ahead in his kayak, which he had packed with a Bible. After that, it is a bit of a mystery what happened.
But the police say one thing is clear: Mr. Chau did not survive.
On Wednesday, the Indian authorities said that Mr. Chau had been shot with bows and arrows by tribesmen when he got on shore and that his body was still on the island. Fishermen who helped take Mr. Chau to North Sentinel told the police that they had seen tribesmen dragging his body on the beach.
It was a “misplaced adventure,’’ said Dependra Pathak, the police chief in the Andaman and Nicobar Islands. “He certainly knew it was off limits.’’
Mr. Pathak said Mr. Chau, believed to be 26 or 27 and from Washington State, may have been trying to convert the islanders to Christianity. Right before he left in his kayak, Mr. Chau gave the fishermen a long note. In it, police officials said, he had written that Jesus had bestowed him with the strength to go to the most forbidden places on Earth.
The Andaman and nearby Nicobar Islands are beautiful, palm-fringed specks ringed by coral in the Indian Ocean. The government controls access very carefully; of the more than 500 islands, many areas are off limits.
On Nov. 14, Mr. Chau hired a fishing boat in Port Blair, the main city in the Andamans, to take him to North Sentinel. He waited until darkness to set off, police officials said, so he would not be detected by the authorities.
T. N. Pandit, an anthropologist who visited North Sentinel several times between 1967 and 1991, said the Sentinelese people — who officially number around 50 and who hunt with spears and arrows fashioned from scraps of metal that wash up on their shores — were more hostile to outsiders than other indigenous communities living in the Andamans.
Once, when Mr. Pandit’s expedition offered a pig to the Sentinelese, two members of the tribe walked to the edge of the beach, “speared it” and buried it in the sand.
During another encounter, Mr. Pandit was separated from his colleagues and left alone in the water. A young tribesman on the beach pulled out a knife and “made a sign as if he was carving out my body.”
“He threatened; I understood,” Mr. Pandit said. “Contact was different with the Sentinelese,” he added, noting that the Jarawa, another tribe, “invited us to come ashore and sang songs.”
Being left alone was very important for the Sentinelese, said Stephen Corry, the director of Survival International, a group that protects the rights of indigenous tribal peoples around the world.
“This tragedy should never have been allowed to happen,” Mr. Corry said in a statement, adding that the Indian government must protect the tribe from “further invaders.”
Gift-giving expeditions to the Sentinelese stopped in 1996. The Indian Navy now enforces a buffer zone to keep people away. In 2006, the Sentinelese killed two fisherman who had accidentally drifted on shore.
Police officials said that Mr. Chau had known that what he was doing was illegal because he had chosen to leave under the cover of darkness.
According to the fishermen who helped him, 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.
The seven people who helped Mr. Chau reach the island have been arrested and charged with culpable homicide not amounting to murder and with violating rules protecting aboriginal tribes.
Another case has been registered against “unknown persons” for killing Mr. Chau. But in the past, the authorities have said that it is virtually impossible to prosecute members of the protected tribes because of the area’s inaccessibility and the Indian government’s decision not to interfere in their lives.
In a blog post from several years ago, Mr. Chau said he had coached soccer, worked for AmeriCorps and that he was “an explorer at heart.” The Indian police said he had visited the Andamans at least three times.
When asked what was the top of his must-do list, Mr. Chau had written on the blog: “Going back to the Andaman and Nicobar Islands in India is on the top — there’s so much to see and do there!”