Legend on da Vinci's "The Last Supper"

It is said that when painting "The Last Supper" Leonardo da Vinci has met a great difficulty: he had to create " the good," in Jesus and "the evil" in Judas. The artist leaves the painting unfinished and continues it, he notices a young man in a church choir, who fits the image of poser for Christ sought by him.
For three years, the artist continues to look for a poser for Judas and one night he accidentally meets a drunkard with dirty, ragged and tattered clothes. With great difficulty the drunkard is dragged to the workshop, where Leonardo, impressed by his evil and cruel face, creates in the image of Judas. When the painter completes the picture, the poor man, who had come to himself a little, says, that he is familiar with that painting.
It turns out that years ago, before losing everything, an artist has created the image of Christ from him.