WASHINGTON — Joseph R. Biden III, the former attorney general of Delaware and the elder son of Vice President Joe Biden (Joseph R. Biden Jr.), died on Saturday in Bethesda, Md. He was 46.
The cause was brain cancer, his father said.
Mr. Biden had spent more than a week receiving treatment at the Walter Reed National Military Medical Center, where he died.
The statement went on to say, “In the words of the Biden family: Beau Biden was, quite simply, the finest man any of us have ever known.”
Officials said in 2013 that the doctors in Texas had removed a small lesion from his brain.
A popular Democratic politician in his home state, who was known to be very close to his father, Mr. Biden served two terms as Delaware’s top law enforcement official before announcing last year that he would not run for a third term so he could make a bid for governor in 2016.