Chau attended Vancouver Christian High School and graduated from Oral Roberts University, a Christian college in Oklahoma, in 2014, with a degree in health and exercise science. While there, he worked with the university's missions and outreach department.

"I have never known a more courageous, selfless, compassionate man and friend," said Bobby Parks, the department's former director. "John lived and gave his life to share the love of Jesus with everyone."

A tribesman aims his bow at an Indian coast guard helicopter as it flew over North Sentinel Island in 2004. Indian Coast Guard via AP file

Chau was involved with Parks' nonprofit, More Than a Game, a soccer program for disadvantaged children, including refugees.

Chau traveled to the Kurdistan region of northern Iraq in 2014 to work with young Syrian and Iraqi refugees. Parks said. He also worked with Burmese refugee children in Tulsa, Oklahoma, for several years.

Casey Prince, 39, of Cape Town, South Africa, met Chau five years ago when they traveled with members of his university's soccer team.

He told the Associated Press that Chau was easy to like, kind, joyful and driven by twin passions: a love of the outdoors and fervent Christianity.

"He was an explorer at heart," Prince said. "He loved creation and being out in it, I think having probably found and connected with God that way, and deeply so."

He said Chau accepted the dangers that came with his travels. "If he was taking a risk, he was very aware of it," Prince said.

Dependra Pathak, director general of police on India's Andaman and Nicobar Islands, said Chau arrived in the archipelago Oct. 16. It was not his first time in the islands, having visited in 2015 and 2016.

Chau organized his visit to North Sentinel through a friend who hired seven fishermen for $325 to take him there on a boat, which also towed his kayak, Pathak said.

The island was completely off-limits until earlier this year, but visits are still heavily restricted and required permissions that Pathak said had not been sought.

The Andaman and Nicobar Islands are located at the corner of the Bay of Bengal and Andaman Sea. Google Maps

The American went ashore in his kayak on Nov. 15 and sent the boat with the fishermen out to sea to avoid detection, Pathak said in a news release. He interacted with some of the tribespeople, offering gifts such as a football and fish. But the tribespeople became angry and shot an arrow at him, hitting a book he was carrying.

Chau swam back to the fishermen's boat and for the night and set out again to meet the tribespeople on Nov. 16.

On Nov. 17, the waiting fishermen watched from a distance as the tribesmen dragged Chau's body.

Pathak said the seven fishermen were charged with endangering the life of the American by taking him to a prohibited area on his “misplaced adventure.”

He was apparently killed by arrows but the cause of death can't be confirmed until his body is recovered, Pathak said.

Police surveyed the island by air Tuesday, and a team of police and forest department officials used a coast guard boat to travel there Wednesday and another trip was planned Thursday, he said.

Survival International, a global advocacy non-profit for tribespeople, described the Sentinelese as an "uncontacted" community of between 50 and 200 people who "vigorously reject all contact with outsiders."

Just five months ago the Indian authorities lifted one key restriction on foreign tourists going to the #Sentinelese tribe's island – the news of an American missionary's death on the island is the tragic consequence. Protect #uncontacted tribes' lands now! pic.twitter.com/R2j9ANezsk — Survival International (@Survival) November 21, 2018

"This tragedy should never have been allowed to happen. Indian authorities should have been enforcing the protection of the Sentinelese and their island for the safety of both the tribe, and outsiders," said Survival International director Stephen Corry. "The Sentinelese have shown again and again that they want to be left alone, and their wishes should be respected."