
This panel is part of the large 'Demidoff Altarpiece' made for the high altar of San Domenico in Ascoli Piceno, east central Italy.
Saint Andrew the Apostle was a fisherman and follower of John the Baptist and was one of the first to follow Christ. His attribute is a cross - usually x-shaped rather than the upright cross he holds here, along with a well-thumbed book.
Crivelli has deliberately placed the cross at an extremely acute angle to show off his skill in perspective drawing. He also takes great pleasure in minute details - use the zoom to look at the nails in the cross, the veins in the hand holding the book, and the saint's slightly strangely shaped ears.