MADRID — The trial of a Bulgarian man who beheaded a British woman with a carving knife in a random attack inside a supermarket on the Spanish resort island of Tenerife in the Canary Islands begins Monday. Deyan Valentinov, a 20-year-old homeless Bulgarian man with a police record, is accused of having entered the store May 13, 2011, grabbed a 9-inch (23-centimeter) ham-slicing knife and then repeatedly attacked Jennifer Joans Mills Westley. Valentinov was captured by security guards after he had run out of the supermarket holding the head. Prosecutors demand he should be sentenced to 20 years in a mental asylum because he has chronic paranoid schizophrenia. Monday's proceedings at the Santa Cruz de Tenerife court begin with jury selection. The trial concludes Feb. 25 with a verdict expected later.