- _Slant_ (1998)
- _Shadow of a Doubt_ (1998)
- _Red Rain_ (1999)
- _The Curse of the Blue Tattoo_ (2000)
- _The Evil One_ (2001)
- _The Devil Inside_ (2002)
- _The Book of Death_ (2003)
- _The Last Dance_ (2004)
- _The Prophecy_ (2005)
- _The Awakening_ (2006)
- _The Reckoning_ (2007)
- _The Chosen One_ (2008)
- _The Armageddon Conspiracy_ (2010)
- _The Final Day_ (2011)
Non-Fiction:
- _The Science of Evil_ (2013)
- _The Reality of Angels and Demons_ (2014)
- _The Search for the Holy Grail_ (2015)
- _The Enigma of the Shroud of Turin_ (2016)
- _The Mysteries of the Dead Sea Scrolls_ (2017)
- _The Secrets of the Vatican Vaults_ (2018)