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Indian authorities were struggling Thursday to figure out how to recover the body of an American killed last week after wading ashore on an isolated island cut off from the modern world.

John Allen Chau was killed by North Sentinel islanders who apparently shot him with arrows and then buried his body on the beach, police say.

But even officials don't travel to North Sentinel, where people live as their ancestors did thousands of years ago, and where outsiders are seen with suspicion and attacked.

"It's a difficult proposition," said Dependera Pathak, director-general of police on India's Andaman and Nicobar Islands, where North Sentinel is located. "We have to see what is possible, taking utmost care of the sensitivity of the group and the legal requirements."

Police are consulting anthropologists, tribal welfare experts, forest experts and scholars to figure out a way to recover the body, he said.

While visits to the island are forbidden, Chau paid fishermen last week to take him to the island. He used a kayak to paddle to shore, bringing gifts including a football and fish.

He interacted with some of the tribesmen — who survive by hunting, fishing and collecting wild plants and are known for attacking anyone who comes near with bows and arrows and spears — until they became angry and shot an arrow at him. The 26-year-old adventurer and Christian missionary then swam back to the fishermen's boat waiting at a safe distance.

That night, he wrote about his visit and left his notes with the fishermen. He returned to North Sentinel the next day, Nov. 16.

What happened then isn't known, but on the morning of the following day, the fishermen watched from the boat as tribesmen dragged Chau's body along the beach and buried his remains.

Pathak said the seven people have been arrested for helping Chau, including five fishermen, a friend of Chau's and a local tourist guide.

"It was a case of misdirected adventure," Pathak said.

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

In an Instagram post, his family said it was mourning him as a "beloved son, brother, uncle and best friend to us." The family also said it forgave his killers and called for the release of those who assisted him in his quest to reach the island.

"He ventured out on his own free will and his local contacts need not be persecuted for his own actions," the family said.

Authorities say Chau arrived in the area on Oct. 16 and stayed on another island while he prepared to travel to North Sentinel. It was not his first time in the region: he had visited the Andaman and Nicobar Islands in 2015 and 2016. North Sentinel is part of the Andaman Islands and sits at the intersection of the Bay of Bengal and Andaman Sea.

With help from a friend, Chau hired fishermen for $325 to take him there on a boat, Pathak said.

After the fishermen realized Chau had been killed, they left for Port Blair, the capital of the island chain, where they broke the news to Chau's friend, who in turn notified his family, Pathak said.

Police surveyed the island by air on 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.

India has a very hands-off approach to the island's people. Tribespeople killed two Indian fishermen in 2006 when their boat broke loose and drifted onto the shore, but Indian media reports say officials did not investigate or prosecute anyone in the deaths.

Chau had wanted ever since high school to go to North Sentinel to share Jesus with the indigenous people, said Mat Staver, founder and chairman of Covenant Journey, a program that takes college students on tours of Israel to affirm their Christian faith. Chau went through that program in 2015.

"He didn't go there for just adventure. I have no question it was to bring the gospel of Jesus to them," Staver said.

Chau was carrying a Bible that was hit by an arrow when he was first shot at by the tribesmen on Nov. 15, according to notes Chau left with the fishermen that Staver said he has seen.

Staver said Chau's last notes to his family on Nov. 16 told them that they might think he was crazy but that he felt it was worth it and asked that they not be angry if he was killed.

One of Chau's friends said the American spent a month at his home in Cape Town, South Africa, before going to India.

"If he was taking a risk, he was very aware of it," said Casey Prince, 39.

The two first met about six years ago, when Chau was a manager on the soccer team at Oral Roberts University in Oklahoma. Chau and others on the team traveled to South Africa to volunteer at a soccer program Prince founded

Prince described him as easy to like and driven by twin passions: a love of the outdoors and fervent Christianity.

Before attending Oral Roberts University, Chau had lived in southwestern Washington state and went to Vancouver Christian High School. Phone messages left with relatives were not immediately returned Wednesday.

Survival International, an organization that works for the rights of tribal people, said the killing of the American should prompt Indian authorities to properly protect the lands of the Sentinelese.

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Associated Press writers Tim Sullivan in New Delhi, Gene Johnson and Phuong Le in Seattle, and Gillian Flaccus in Portland, Oregon, contributed to this report.