Dateline: What Happened in the Basement revisits the 2018 murder of Amy Allan, who was found hanging by an extension cord in the basement of her Michigan house, by her husband, Jimmy Allan. The case was also featured in a 2022 episode of Dateline: The Last Day, titled The Case of Amy Allan.While Jimmy maintained that his wife had committed su*c*de after their heated argument on the night of September 14, 2018, the truth was far more sinister and shocked Allan's family.As Michigan State Police Detective Larry Rothman recalled on Dateline, the investigators were suspicious of Jimmy Allan and his account from the beginning. While Jimmy claimed Amy Allan was already hanging when he found her in the basement, the low height of the basement's ceiling brought his story under scrutiny. It was only after Rothman pursued the chilling evidence from the basement that Amy Allan's true killer came to light. Rothman said:"This was physical evidence, scientific physical evidence that proved that Jimmy’s story just didn’t add up."Here's how Dateline: What Happened in the Basement presented Amy Allan's murder case.Dateline: What Happened in the Basement- The clue that exposed Amy Allan's killerAfter Amy Allan's first son, Caleb, moved in with his grandparents, she relocated to Michigan with Jimmy Allan and their teenage daughter, Ashley. The couple decided to move after Jimmy got an impressive job in Michigan doing video production for an audio accessories company. But trouble followed the couple to Michigan and came to a head on the evening of September 14, 2018.Things took a turn when Jimmy suggested another move to North Carolina, a suggestion that resulted in a heated argument.As featured in Dateline: What Happened in the Basement, Jimmy discovered his wife hanging in the basement at 8:40 p.m. Amy Allan was still alive when Jimmy called 911, and she was taken to the hospital. Amy's family shared their suspicions about Jimmy when he did not inform them about the alleged su*c*de. But the family managed to bid farewell before Amy Allan succumbed to her injuries and died.Dateline: What Happened in the Basement revealed that Michigan police suspected Jimmy and his account of the night. Rothman turned his attention to the low height of the ceiling and shared his concerns with a forensic engineering lab. The investigators wanted to confirm if a woman with Amy's height could hang herself from the low ceiling with an extension cord, as Jimmy described.Rothman's hunch was confirmed when the lab conducted tests showing that Amy Allan couldn't hang herself. Even if she had decided to hang herself, the extension cord would have stretched, and her feet would have hit the ground.On Dateline: What Happened in the Basement, Rothman recalled how the unexpected physical evidence exposed Jimmy Allan's lie:“With the extension cord and the height of this basement, it just didn’t add up that she could have hung herself in the way it was described by Mr. Allan."While pathologists found no external injuries on Amy Allan's neck, notable marks were found on the interior of her neck, similar to a chokehold. On Dateline: What Happened in the Basement, Caleb shared a theory about why his stepfather took this drastic step:“I think when she got in that house, she raised h*ll and I think it pushed him to a point where he hadn’t ever been to before and I think he went a little too far and then just kept going."After a pathologist ruled Amy Allan's death a homicide, Jimmy was arrested in 2020. While Jimmy maintained that he was innocent and Ashley testified in her father's support, he was found guilty of second-degree murder by the jury in September 2021 and was sentenced to 20 to 45 years in prison.You can stream Dateline: What Happened in the Basement on Peacock.For the latest scoops on your favorite TV shows and movies, follow SoapCentral.