TrafficBollard

Hi Last year I picked up a book in a store in Kuala Lumpur which sounded great but which I did not buy. I went in a week later and couldn't find it. I had by that time forgotten the title of the novel and the name of the author. I am trying to find it by describing the plot to people on book forums in the hope that someone might recognise the work, so here goes: The novel, I'm pretty sure, is French (English translation). It was a very slender tome and I think the author's surname began with L (though I couldn't swear to it). The synopsis, so far as I can piece it together, is as follows: An anthropologist travels to a remote island jungle (South Pacific?) where he joins a native tribe. He marries and fathers a child. However, his interest in his anthropological project compels him to murder the child (and possibly the wife) and confess the crime to his newfound brethren. His motivation for doing so is connected to an important moral dilemma, namely: if the tribe are convinced of his guilt and put him to death then civilisation wins out. If they don't care then man is no different from the beasts in the fields, and the protagonist will sink into despair though his life will be spared. Ring any bells? I'd be very grateful for any help you can give me.