The death of Kathleen Peterson led to not just one of the most infamous murder trials but one of the most prolonged. Kathleen's husband, Michael Peterson, just recently walked free, a decade and a half after her death, but some people still think he's responsible. Others, as you'll see below, say an owl is a real culprit. And now Investigation Discovery is reexamining the case with An American Murder Mystery: The Staircase.

Here's the backstory: In the early morning hours of Dec. 9, 2001, a then-58-year-old Mike called 911 to say his 48-year-old wife had fallen down a staircase at their home in Durham, NC. Mike — a novelist, a military veteran, and a one-time Durham mayoral candidate — said he'd come in from the backyard to find her dead. And he said she'd been drinking. Sure enough, her blood alcohol level was 0.07, but the autopsy report also determined she'd suffered head trauma consistent with a beating.

Police arrested Mike and charged him with murder. During the 2003 trial, the district attorney claimed Mike killed Kathleen after she discovered he was having an affair with a man. But the defense argued Kathleen knew about and had accepted Mike's bisexuality. Mike also seems to have trumped up his military record, as the prosecution pointed out. He had previously claimed he had won a Silver Star, a Bronze Star with Valor, and two Purple Hearts; but he could only verify receiving one Purple Heart.

Perhaps the most damning evidence, however, was the 1985 death of Mike's friend Elizabeth Ratliff. Mike and his wife at the time had dined with Elizabeth the night before she found dead at the foot of a staircase — circumstances eerily similar to Kathleen's demise — and the Petersons got legal guardianship Elizabeth's two children. During the trial regarding Kathleen's death, Elizabeth's body was exhumed and re-examined. And this time, a medical examiner determined Elizabeth had died by homicide. The prosecution argued this was evidence Mike knew how to fake an accident.

The jury in the 2003 trial convicted Mike, and he was sentenced to life in prison without the possibility of parole. As Mike repeatedly appealed the conviction, a neighbor and lawyer named Larry Pollard noticed a lab reported mentioned a feather. He speculated Kathleen was attacked by an owl before falling down the staircase. Turns out, owl attacks were common in the neighborhood, and Kathleen's autopsy showed she was holding clumps of her own hair in her hands — one of which contained feathers — and had pine needles stuck to one hand. Also, some people believe her head lacerations are consistent with talon injuries.

The owl theory never took flight, so to speak, but Larry and Mike's attorneys worked together to find prosecutorial flaws from the original trial. They were successful, especially because blood analyst Duane Deaver was found to have misreported results, withheld results, or overstated the strength of evidence in 34 cases.

Mike was released from prison in 2011 and placed under house arrest. His new trial was scheduled for May 2017, but in February 2017, Mike entered an Alford plea to voluntary manslaughter — i.e. he acknowledged there was enough evidence for a voluntary manslaughter conviction and pleaded guilty but still maintained his innocence. The judge in the new trial sentenced Mike a maximum of 86 months in prison and gave him credit for the 89 months he had already served, so Mike walked free.

The case became a national talking point, especially after the release of a French TV documentary titled The Staircase. Now, Investigation Discovery is revisiting the saga. "The death of Kathleen Peterson is one of the most confounding cases in history," ID exec Henry Schleiff says in a statement. "There are so many pieces to this puzzle — from Michael's salacious secrets to investigator misconduct to the odd owl theory. We are eager to bring our viewers the first complete look at this fascinating crime and subsequent trial." The three-part series American Murder Mystery: The Staircase premieres on ID on Sunday, April 8, at 10 p.m. ET.

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