Sandy Parsons, the adoptive father of Erica Parsons, took the polygraph on the "Dr. Phil" show and denied he either deliberately caused or planned the girl's disappearance.
Polygraph expert Jack Trimarco, who administered the test, said he thought Sandy Parsons was being deceitful, The Charlotte (N.C.) Observer reported Wednesday.
"He was what I consider strongly deceptive to both relevant questions," Trimarco told the host, Dr. Phil McGraw.
"Do you think he knows something he's not telling us?" Dr. Phil asked.
"He does," Trimarco responded.
Trimarco said on the show he explained the meaning of the questions and Sandy Parsons understood them, but an attorney for Sandy Parsons and his wife Casey said Sandy Parsons may have misunderstood the questions during the polygraph examination.
"We know that there are problems in what Sandy and Casey have been saying as far as logically," Carlyle Sherrill said. "I don't know if he misinterpreted the question as far as the fact that they did, in fact, deliver her [to her grandmother] and she's gone now."
Erica Parsons has been missing since 2011, when she was 13 years old, but her disappearance was not reported until two weeks ago, when her adoptive brother reported it. Her parents maintain they last saw her when they dropped her off at her grandmother's home.
Notable deaths of 2014 [PHOTOS]