By all accounts, Chris Johnson and Andrea Cincotta were the picture-perfect image of an engaged couple. But everything changed one tragic night in August 1998, when Johnson found his fiancée lifeless in a closet in their shared apartment. Police peg Johnson as the killer after he confesses during interrogations that spanned 28 hours over three days. But when the details fail to add up, they are left asking: Who really killed Andrea Cincotta? A new “20/20” reports on the twists and turns in the investigation; an exclusive interview with Johnson, who discusses his dealings with the police; what it was like to eventually stand trial for allegedly hiring the man who confessed to killing Cincotta; and how he has navigated a falling out with Kevin, Andrea’s son from a previous marriage, who still holds him responsible ― even after a jury found Johnson not guilty.