BOSTON --A hotel employee fatally stabbed a co-worker after an argument Friday afternoon, Boston police said. Police said the male victim was found in an employee area of the Westin Copley Place in Boston's Back Bay at about 4:30 p.m. The man, who was about 30, was taken to the Boston Medical Center where he was pronounced dead, police said. Police have not released his name. Ivan Sosa, 37, of Boston's Dorchester neighborhood was arrested and faces murder and assault charges, police said. He was to be arraigned Monday morning.