The trail of a child kidnapping in 2007 led to an apartment in Kirkwood, Missouri, where Shawn Hornbeck, missing for more than four years, was found too.
Interrogator was an FBI polygraph examiner, attuned to detecting subtleties that wave a red flag.
Six years after his own rescue and now 21, he offers advice to those discovered in Cleveland case.
"He became too defensive, " officer says of Michael Devlin. "Something didn't feel right."