IE 11 is not supported. For an optimal experience visit our site on another browser.

DATELINE WEEKEND MYSTERY SNEAK PEEK: While He Was Sleeping

01:54

When a luxury car dealer is found dead, detectives suspect one of his lovers, but lack of evidence stalls the case for a year, until one clue breaks it wide open. Josh Mankiewicz reports Saturday, May 8th at 8/7c on NBC.