How do you expect the painting to "turn out" to be by Peter Doig, if he is lying? What he would have us believe is that there was another young man with 90% the same name who painted a landscape that the senior Contemporary expert called "Wonderful early Peter Doig", and by coincidence they were both from Canada and it just happened to be the one year of his life when Doig was not in school or working.
Oh, and the inmate had been busted for LSD. Doig has paintings named Blotter, Windowpane and Orange Sunshine.