Robert K. Ressler (1937-2013) was a supervisory special agent of the FBI as a reserve colonel in the U.S. Army's Criminal Investigation Division (CID) before retiring. He later served as the director of Forensic Behavioral Services, a business dedicated to training, learning, consulting, and expert witness testimony. He is the author of Whoever Fights Monsters and the inspiration for one of the main characters in the Netflix Original Series Mindhunter. Tom Shachtman is the co-author with Robert Ressler of Whoever Fights Monsters and Justice is Served. He's also the author of several books of history, including How the French Saved America.
"The real thing . . . Absolutely mesmerizing." --Ann Rule "A true crime bonanza." --Kirkus "An invaluable book for anyone who wants to understand serial murder." --Joseph Wambaugh