Steven Williams, a 30-year-old U.S. Air Force staff sergeant stationed at Seymour Johnson Air Force Base in North Carolina, has confessed to killing his ex-wife, Tricia Todd, on the night of 26 April 2016. Williams reportedly dismembered Todd with a chain saw and buried her body parts in an acid-filled container in a pre-dug grave in a Florida nature preserve.

Despite having committed a premeditated murder, on or about 3 May 2016, Williams passed a polygraph “test” about his ex-wife’s disappearance. As Huffington Post senior crime reporter David Lohr noted on 5 May:

A search of Williams’ car showed nothing unusual, authorities said, and he passed a polygraph examination. “He did voluntarily submit to a polygraph exam,” [Martin County, Florida Sheriff William] Snyder said. “Nothing in Mr. Williams’s lengthy interview — and it was a long, detailed interview — nor his polygraph exam indicated that he was involved or had any additional information about Tricia Todd’s disappearance.” Snyder added that “at this point, there is no focus that needs to be on the former husband.”

It would appear that Williams’ passing the polygraph helped to misdirect investigators, at least temporarily. Williams ultimately confessed to killing Todd and agreed to lead investigators to her remains as part of a plea arrangement which will see him incarcerated for 35 years.

Steven Williams’ fooling the polygraph after committing such a monstrous act calls to mind the case of “Woodchipper Killer” Richard Crafts, who passed a polygraph “test” despite having killed his wife, Helle Crafts, dismembered her body with a chainsaw, and ground up the parts with a commercial woodchipper.

It would be a mistake to rationalize away these failures of the polygraph to detect deception by saying, “well of course they passed, they were psychopaths who felt no remorse for their actions.” The fact of the matter is that there is little evidence regarding whether psychopaths have any special advantage when it comes to beating polygraph “tests.” The important thing to understand is that polygraphy has no scientific basis whatsoever.

Polygraph methods were devised by interrogators who had little understanding of the scientific method, and anyone can fool the polygraph using simple countermeasures that polygraph operators cannot detect. Polygraph countermeasure techniques are documented in Chapter 4 of AntiPolygraph.org’s free book, The Lie Behind the Lie Detector (PDF).