Johnson worked on the presidential election campaign of United States Senator Robert F. Kennedy, and on June 5, 1968 with the help of Rosey Grier, he apprehended Sirhan Sirhan immediately after Sirhan had assassinated Kennedy at the Ambassador Hotel in Los Angeles, California. Kennedy died the following day at Good Samaritan Hospital. Johnson discussed the experience in his autobiography, "The Best That I Can Be" (published in 1999 by Galilee Trade Publishing and co-authored with Philip Goldberg).