Chau, who has been described as a mountaineer and Christian missionary, was reportedly killed by members of the tribe on November 17 after previously making contact with the indigenous group a few times. Citing notes Chau gave to fishermen who aided him in his travels, Reuters reported that the adventurer had met with the tribe two or three times before returning to a fishing boat.
"What has happened is not very clearly spelled out in his notes, but it is indicative of his deep expedition planning and his determination to contact these aborigines despite knowing he would face vigorous rejection," Dependra Pathak, the director general of police for the Andaman and Nicobar Islands, which is governed by India, told Reuters.
So far, a total of 7 individuals have been arrested, police noted in a Wednesday statement. Two of those individuals were friends of Chau's and the five others were fishermen. The fishermen later told investigators that after returning to the island on the morning of November 17, they saw Chau's body being dragged across the beach by a member of the Sentinelese tribe.
"The fishermen saw a dead person being buried at the shore, which from the silhouette of the body, clothing and circumstances appeared to be the body of John Allen Chau," the police noted in their release. Rather than immediately contacting police, the group of fishermen instead returned to Port Blair to contact Chau's friends who then reached out to his mother.
A missing persons report and subsequent investigation was not launched until after Chau's mother reached out to the US Consulate General in Chennai, India, on November 19.
Police are now looking to determine whether or not there were additional people who may have assisted Chau in reaching the protected island, Vijay Singh, the senior superintendent of police in the Andaman and Nicobar islands, told Reuters.
The investigation is also expected to zero in on the events that took place leading up to Chau's death and the exact sea route that was followed by the group, as well as other items of interest. According to the Independent, officials have allegedly begun reconnaissance of the island to better understand what took place.
Chau's family has most recently called on authorities to release those who've already been detained, writing on the missionary's Instagram page, "[Chau's] local contacts need not be persecuted for his own actions."
"He ventured on his own free will," the statement reads.
However, despite the family's request, officials intend to follow through with their investigation. "I understand the emotional concern of the family… but we'll be handling the entire issue keeping in mind the law," Pathak told Reuters.
Officials are also looking into the possibility of recovering Chau's body. However, in 2006, two fishermen were killed by the tribe and their bodies were never recovered, despite attempts by the Indian Coast Guard to do so.
"The Sentinelese enjoy unfettered rights over the resources available in their reserve area for their sustenance, and entry into Sentinelese Tribal Reserve by non-tribals and others are strictly prohibited," a senior official from the Ministry of Home Affairs, who did not wish to be named, previously told Sputnik.
North Sentinel Island is protected by laws which prohibit fishing within 5 nautical miles of the island and tourism in an effort to protect both outsiders and the natives, as the tribe is known to be somewhat hostile. Individuals found to have broken the law can face up to three years in jail, according to the Independent.