In May, 1997, his in-depth investigation of UFOs, Alien Agenda, was published by HarperCollins Publishers. Lauded as the most comprehensive and documented work of its kind, Alien Agenda went into a third printing within a month of publication.

Marrs is listed in both Who's Who in the World and Who's Who in America. He has won several writing and photography awards including the Aviation/Aerospace Writers Association's National Writing Award and Newsmaker of the Year Award from the Fort Worth Chapter of the Society of Professional Journalists. In 1993, Marrs received Freedom magazine's Human Rights Leadership Award.

He has appeared on hundreds of national and regional TV and radio programs including This Morning America, Geraldo, Montell Williams, Today, Good Morning Texas and the Larry King and Art Bell radio shows. A former president of the Press Club of Fort Worth and a current member of the Society of Professional Journalists, Sigma Delta Chi, and Investigative Reporters and Editors, Marrs has spoken out on a variety of conspiracy topics including the TWA 800 crash, the Waco tragedy, the Oklahoma City bombing, terrorism and covert government operations.