The FBI Plot (Holloway House, 1981)
Mass Murder (Garland, 1988)
Terrorism in the United States and Europe (Garland, 1988)
How to Write Action/Adventure Novels (Writer's Digest, 1989)
FBI Most Wanted (Garland, 1989; Dell 1993)
The Ku Klux Klan (Garland, 1991)
Racial & Religious Violence in America (Garland, 1991)
Raising Hell (Avon, 1993)
Rope (Pocket Books, 1998)
Cop Killers (Loompanics, 1998)
The Encyclopedia of Unsolved Crimes, 2nd ed (FoF, 2009)
Crime & Criminals (Checkmark, 2010)
Crime-fighting & Crime Prevention (Checkmark, 2010)
Bomb Squad (Checkmark, 2010)
SWAT Teams (Checkmark, 2010)
Texas Rangers (Checkmark, 2010)
US Marshals (Checkmark, 2010)
DEA (Checkmark, 2010)
Prison and the Penal System (Checkmark, 2010)
True Crime: Gangsters--Outside the Law (Igloo Books, 2010)
When Bigfoot Attacks (CFZ Press, 2011)
Strange Pennsylvania Monsters (Schiffer, 2012)
Globsters (CFZ Press, 2012)*
The Mafia at Apalachin (McFarland, 2011)
Ku Klux Terror (Schiffer, 2013)*
Writing Westerns (Writers Digest ebooks, 2012)
Writing Thrillers (Writers Digest ebooks, 2013)*
Strange Ohio Monsters (Schiffer, 2013)*
Famous Assissinations in World History, and Encyclopedia (ABC-Clio, 2014)**
Hoaxed (CFZ Press, 2013)*
The Texarkana "Moonlight Murders" (McFarland, 2014)*
Hate Crimes in America since 1968 (McFarland 2015)**