This is Pt 2/2 of the series. You can find Pt 1 here.

Tracy Harpster, a deputy police chief from suburban Dayton, Ohio, was hunting for praise. He had a business to promote: a miracle method to determine when 911 callers are actually guilty of the crimes they are reporting. “I know what a guilty father, mother or boyfriend sounds like,” he once said.

Harpster tells police and prosecutors around the country that they can do the same. Such linguistic detection is possible, he claims, if you know how to analyze callers’ speech patterns — their tone of voice, their pauses, their word choice, even their grammar. Stripped of its context, a misplaced word as innocuous as “hi” or “please” or “somebody” can reveal a murderer on the phone.

So far, researchers who have tried to corroborate Harpster’s claims have failed. The experts most familiar with his work warn that it shouldn’t be used to lock people up.

Prosecutors know it’s junk science too. But that hasn’t stopped some from promoting his methods and even deploying 911 call analysis in court to win convictions.

Archive link: https://archive.ph/vIjHo