Bizarre self-taught "professional engineer" of execution methods. He became a professional execution consultant and did consulting work on various US states' death chambers.

He later wrote a controversial holocaust denying report in 1988 for Ernst Zundel that stated Zyklon B was not used to kill humans. His findings were discredited because Leuchter made many factual errors (indeed, he had no formal training in engineering, chemistry or toxicology but instead obtained a BA in history in 1964). Nizkor.org thoroughly discredited the Leuchter Report online.

Leuchter was the subject of the 1999 Errol Morris documentary: "Mr. Death: The Rise and Fall of Fred A. Leuchter, Jr.".