Image:Who are the SentineleseIndian officials are facing a difficult task to retrieve the body of an American missionary reportedly killed by an endangered tribe in the Andaman and Nicobar islands.A police boat faced off with Sentinelese tribesmen on Saturday but withdrew to avoid confrontation.John Allen Chau was said to have been killed with arrows when he landed on North Sentinel.He was trying to convert the protected people to Christianity.The fishermen who ferried Chau, 27, to North Sentinel on 17 November said they saw tribesmen drag a body along a beach and bury it.The fishermen later accompanied police back to the point on the island where they believed the body was buried.Six fishermen and one other person have been arrested over the incident.On Saturday, police stationed their boat about 400m (437 yards) offshore and, using binoculars, saw tribesmen on the beach armed with bows and arrows.Regional police chief Dependra Pathak told Agence France-Presse: "They stared at us and we were looking at them."The boat then withdrew."We have mapped the area with the help of these fishermen.

We have not spotted the body yet but we roughly know the area where he is believed to be buried," Mr Pathak said.Image copyrightSurvival International Image caption Few images of the endangered tribe exist Image copyrightChristian Caron - Creative Commons A-NC-SAImage caption The Sentinelese stand guard on an island beach in 2005 Outsiders are banned from even approaching the island so as to protect the people who live there, and their way of life.The complete isolation of the Sentinelese people means contact with the outside world could put them at risk, as they are likely to have no immunity to even common illnesses such as flu and measles.The tribesmen have treated outsiders with hostility for years.In 2006, two fishermen were killed and their bodies placed on bamboo stakes, Mr Pathak said.Those bodies were recovered but fears remain that Chau's may never be retrieved.A murder case has been registered against unknown persons but it has not been suggested tribesmen will face any charges.Chau's family have said they forgive those who killed him.