Asked to testify before the Joint Committee on Atomic Energy on the danger of radiation causing cancer, Graves replied:  Graves was a pillar of the Los Alamos community. He was an active member of the non-denominational Protestant Community Church. With the encouragement of Elizabeth, who played the violin, he learned to play the cello, hoarding his petrol ration stamps so that he could travel to Santa Fe, New Mexico, for lessons. He played in the Los Alamos Symphony, accompanying local performances of Gilbert and Sullivan and Handel's "Messiah". He was chairman of the board of the local bank, and a member of the local school board. Graves died of a heart attack on July 19, 1965, while skiing in Del Norte, Colorado, twenty years after the Slotin accident, at the age of 55. He had suffered from hypertension even before the 1946 accident, and had a minor heart attack in December 1955. His father had also died of a heart attack. A 1978 follow-up study of the Slotin accident victims suggested that latent systemic damage from the accident contributed to heart failure. He was interred in the Guaje Pines Cemetery in Los Alamos, New Mexico.