WEST LAFAYETTE, Ind. - Manti Te'o was likely telling the truth when he opened up to Katie Couric how he was duped in an online hoax, a Purdue University facial recognition expert said.

Chris Kowal, who uses technology to reveal a speaker's emotions by deciphering hundreds of facial muscle micro-movement, said Te'o's face consistently displayed anger, sadness and disgust when discussing how hoaxers "catfished" him into believing he had a long-distance girlfriend who died of leukemia.

"His strongest emotion was definitely anger," said Kowal, an assistant professor of retail sciences at Purdue. "He was extremely angry that this had happened to him and he was also very, very sad. "

Kowal said he also found that Te'o displayed strong emotions of sadness and anger at a news conference in December where Te'o still talked as if his girlfriend were real, despite having recently learned she was not.

"He may have been in denial about the hoax," Kowal said.

"After processing many different videos of Te'o to create a baseline of facial expressions, no deception is indicated," said Kowal. "I really believe that he is being very sincere."

Te'o conceded to Couric that he should have been more forthcoming when the situation began to unravel, but he denied having any involvement in creating or perpetuating the hoax for his own gain.