Relationship with the Kennedy's
Dinis was a long-time friend of the Kennedy family. He was often seen discussing government and politics with the Kennedy brothers. In 1958 Attorney Dinis helped U.S. Senator John F. Kennedy campaign for re-election to the Senate. In 1966, Senator Edward M. Kennedy even offered assistance to Democratic nominee Edmund Dinis after he won the Primary vote for Southern Massachusetts District Attorney.
Dinis was the district attorney for the area that included Cape Cod and the islands off the coast of Massachusetts. This was where a car driven by Mr. Edward Kennedy plunged off a narrow bridge into a saltwater pond on Chappaquiddick, near Martha's Vineyard, on July 18, 1969. In April 1970, Dinis brought the case before a grand jury. After meeting for two days and hearing less than 20 minutes of testimony from four witnesses, the jury voted not to indict.
After handling this case, Dinis decided to leave office in 1970 to pursue other projects.