GREENVILLE, Del. (AP) - President Joe Biden on Saturday commemorated the 49th anniversary of the car crash that killed his first wife and infant daughter, visiting their graves at the Saint Joseph on the Brandywine Roman Catholic Church.Their deaths occurred just after Delaware voters elected Biden to the Senate in 1972 and the fatal car crash became a defining moment that has shaped his persona and career.His sons Beau and Hunter, ages 4 and 3 at the time, were seriously injured but survived the crash.