Sunday, Jan. 10: Two Chris Hansen investigations

In the first in-depth report on the thwarted Christmas terrorist attack, Chris Hansen investigates the main suspect in the case, and takes viewers through the events of what happened - and what could have happened - that day, and why so many warning signs went ignored. The report includes interviews with passengers and officials, and the first television interview with someone who spent time with the suspect while he was here in the U.S in 2008.

Then, double or nothing -- Hansen is back with another compelling hour on the Las Vegas undercover police operations where he gets exclusive access to go undercover with hidden cameras and confront criminal suspects.

See it all on a special Sunday Dateline NBC from 7-9 p.m. ET.