During the 1960s, he became more politically active and worked on Robert F. Kennedy's Democratic presidential campaign. He was present on the night of June 4/5, 1968, at the Ambassador Hotel in Los Angeles at the time of Kennedy's assassination. During the same year, he discovered the woman who had raised him was his grandmother, not his mother as he thought, and learned that the woman he thought was his sister was actually his mother. Those events deeply affected Darin and sent him into a long period of seclusion.