Police say the two American citizens flew into Port Blair and met Mr Chau between November 6 and 10.
Two weeks after American national John Allen Chau was killed by primitive tribes in the Andamans, startling facts are emerging about his visit there.
Two American citizens had flown into Port Blair and met Mr Chau between November 6 and 10, egging him on, it is suspected, to go to the North Sentinel island.
Police are now investigating the two Americans - Bobbie, a woman in her 50s, and Christian, a youth in his 20s, from Colorado and Tenesse, and members of the same church as Chau -- All Nations Church headquartered in Kansas City.
Police are examining the legal culpability of the two in Mr Chau's death.
He was of "wavering mind", his journal indicates, one moment scared of going to North Sentinel, fully aware of the dangers, another moment ready to go home. Did anyone influence him or force him to go to the forbidden island is a troubling question.
In his journal, Mr Chau writes in a postscript, "Please send all pages of the journal entries to Bobby and tell him forward the current update to All Nations."
"All Nations (www.allnations.us) is an international Christian missions training and sending organization committed to preparing Christians to share the gospel and establish churches in parts of the world where the name of Jesus Christ is little or not known," according to its website.
"All Nations aspires to see disciple making movements in every people group of the world so that Jesus may be worshipped by every tongue, tribe and nation."
Lamenting Mr Chau's death, an official, Dr Mary Ho, said in a statement on the website that, "All Nations is deeply saddened by this news and wants to publicly express our deepest sorrow for this monumental loss. We have been in contact with John's family and ... with the U.S. State Department and continue to cooperate fully with all international, national and regional officials."
According to sources, the two Americans flew out on November 10 and Mr Chau was supposed to sail to North Sentinel a day later. He had to postpone his final journey to November 14 because of bad weather.
Mr Chau took with him footballs for children, fishing lines for the men and safety pins - yes, safety pins - all this, apparently on the advice of a fellow evangelist who had contacted tribals in the Amazon forests and met with some success, sources added.
The tribals apparently use safety pins to dig out slivers of stone and wood that get embedded into their bare feet.
There is more. Mr Chau spent a week at Hut Bay Island before the two Americans arrived and police suspect it was not for tourism but to make contact with the Onge tribe that lives on part of the island, sources said.
Meanwhile, top anthropologists are expected in Port Blair on Monday. They will consult with authorities and take a call on what to do about recovering Mr Chau's body. Senior anthropologists have urged that the body be left alone. The police also said their policy was of not landing on North Sentinel Island and zero confrontation.
Another detail that all quarters are coming to terms with is, the decomposition of the body. Because of the saline sand and insects and crabs on the beach where he is buried, the body is possibly too decomposed to be retrieved.
A final decision will be taken in the next few days.