The All-American linebacker said he was truly sorrowful and pained after finding out the woman he knew as Lennay Kekua died in September.
Te'o's once-heartwarming tale of inspired play after the deaths of his grandmother and girlfriend on the same day in September was exposed as a bizarre hoax on Jan. 16.
Deadspin.com broke the news that the woman Te'o had claimed to be in love with did not exist.
Te'o, who led Notre Dame to a spot in the national championship, has admitted that when his girlfriend's "death" became a story, he misled reporters into thinking he had met her in the flesh.
The star player recounted the whole, strange episode in an interview with Couric that was broadcast Thursday.
Pressed by Couric to admit that he was in on the deception, Te'o said he believed that his girlfriend Lennay Kekua had died of cancer and didn't lie about it until December.
"Katie, put yourself in my situation. I, my whole world told me that she died on Sept. 12. Everybody knew that. This girl, who I committed myself to, died on Sept. 12," Te'o said in the interview.
The Heisman Trophy runner-up said he only learned of the hoax when he received a phone call in December from a woman saying she was Kekua.