James DiEugenio first became interested in history while at film school. Later he studied Contemporary American History from California State University, Northridge.

His first book, Destiny Betrayed (1992) took a close look at the Jim Garrison investigation of the assassination of John F. Kennedy. In 1993, he became a co-founder of Citizens for Truth about the Kennedy Assassination. The following year he was co-founder of the Coalition on Political Assassinations (COPA).

DiEugenio and Lisa Pease co-edited COPA's journal, Probe Magazine (1993-2000). DiEugenio is also the co-editor of The Assassinations (2002), a book that covers the deaths of John F. Kennedy, Martin Luther King, Robert Kennedy, and Malcolm X.