The Staircase Murder of Kathleen Peterson: What Really Caused Her Death?

In December 2001, Kathleen Peterson's body was discovered in a pool of blood at the foot of stairs in her Durham, North Carolina, home. In October 2003, her husband, Michael Peterson, was convicted of first-degree murder for her death.

Peterson's conviction was vacated in December 2011 because a state blood analyst had misled the jury. In February 2017, a 73-year-old Peterson accepted an Alford plea for voluntary manslaughter. Peterson had always said he didn’t kill his wife, and this plea allowed him to still maintain his innocence.

Though the case is closed, questions remain about Kathleen's murder.

Michael and Kathleen Peterson spent the evening of December 8, 2001, together. Peterson, then 58, was a successful writer; Kathleen, then 48, a telecommunications executive. Their marriage, a second for both, seemed happy.

At 2:40 a.m. on December 9, 2001, Peterson called 911 to say he'd found his wife's body at the bottom of a staircase. Investigators considered Kathleen's death suspicious because there was a great deal of blood at the scene.

The medical examiner found that Kathleen's scalp had seven deep lacerations. The death was ruled to be the result of blunt force trauma.

On December 20, 2001, Peterson was indicted by a grand jury for first-degree murder.

Peterson's murder trial began in July 2003.

Pictures of naked men had been found on Peterson's computer, as had communications about Peterson meeting a man for sex. The prosecution contended Kathleen could have discovered this information and confronted her husband about his bisexuality.

The defense argued the Petersons had a happy marriage.

Kevin McMunigal, a criminal law professor at Case Western University's School of Law and former federal prosecutor, tells A&E that introducing Peterson's bisexuality was "pretty relevant in terms of how happy their marriage was, and whether or not they were arguing, but it also was very prejudicial."

"You could imagine, especially back then, there could be some jurors who would condemn him for that…and maybe decide the case on an emotional basis," says McMunigal.

Prosecutors also brought up Peterson's ties to an earlier death.

Elizabeth Ratliff, 43, was a close Peterson family friend who died in Germany in 1985. Like Kathleen, she'd been found at the bottom of a staircase. Peterson had been at her house the night before her death. He later adopted Ratliff's two daughters, Martha and Margaret.

German investigators ruled Ratliff had died due to a cerebral hemorrhage. But in 2003, the same medical examiner who'd performed Kathleen's autopsy conducted a second autopsy on Ratliff's exhumed body. The examiner concluded she had been beaten to death, like Kathleen. No one was ever charged in Ratliff's murder.

A large part of the prosecution's case relied on blood spatter evidence. An analyst from the State Bureau of Investigation (SBI) stated that droplet patterns found on the walls and steps of the stairs at the Peterson house matched what would result from a beating.

Jennifer Shen, retired director of the San Diego Police Department Crime Laboratory, tells A&E Crime + Investigation, "This particular field [of blood spatter reconstruction] should be approached with great caution and scientific reservation."

"An analyst will use scientific principles, experience and training, but ultimately they are deriving their best scientific guess as to what actions occurred to create the evidence viewed at the scene," says Shen. "This…leaves a broad spectrum of interpretations based upon someone's experience, training and, frankly, self-confidence."

The murder weapon has never been found. According to the prosecution’s blunt-force theory, the likely weapon was a long, thin, rounded object—initially presumed to be the home’s fireplace blow poke, which was missing during the early investigation. But the blow poke turned up in the home’s basement late in the trial, and was admitted into evidence by the defense, showing no sign of having been used in a murder.

The defense team argued Kathleen had died after she fell at least two times on the dimly lit stairs, hitting her head repeatedly on sharp molding, after drinking wine and taking Valium. She was wearing flip-flops. They also raised doubts about the prosecution’s assumption that blunt-force trauma had caused her death. Despite having lacerations on her skull, the defense pointed out, Kathleen had suffered no skull fracture and no brain injury or swelling, which typically occur with blunt-force injuries.

Following a three-month trial, Peterson was found guilty October 10, 2003. He was sentenced to life in prison without parole.

Peterson was sent to North Carolina's Nash Correctional Institution. While he was behind bars, his attorneys filed multiple unsuccessful appeals.

In 2009, an attorney who was Peterson's neighbor, T. Lawrence Pollard, filed a motion with a new theory for Kathleen's death: She had been injured by an owl before falling down the stairs. Her scalp wounds supposedly had been caused by the owl's talons.

Pollard found a single, microscopic feather listed in an SBI crime lab report. He submitted a motion stating there were more feathers in hair found in Kathleen's left hand.

The owl theory drew attention, and ridicule, but did not result in a new trial for Peterson.

Then a 2010 independent report revealed multiple cases of distorted or false evidence from the SBI's blood analysis unit. Peterson's case wasn’t among those listed in the report, but the blood analyst who'd testified at his trial was involved in many of those cases.

On February 14, 2011, Peterson filed a motion for a new trial.

On December 14, 2011, the judge who'd overseen Peterson's first trial vacated his conviction due to "materially misleading" and "deliberately false" testimony from the blood analyst.

Peterson, who had spent eight years behind bars, posted bail. He was released on house arrest on December 16, 2011.

Prosecutors appealed the overturning of Peterson's verdict, but North Carolina's Court of Appeals upheld the decision in July 2013. The state Supreme Court chose not to hear the case.

Peterson's lawyers tried to have the case against their client dismissed because physical evidence from the investigation had not been properly preserved. This was denied in November 2016.

Peterson was tentatively scheduled to go on trial in May 2017. In court, the owl theory could have been part of his defense. "It might create reasonable doubt," McMunigal says.

But on February 24, 2017, Peterson entered an Alford plea to voluntary manslaughter in Kathleen's death. He still said he didn't kill his wife, but an Alford plea allows people to continue to maintain their innocence while accepting there is enough evidence to convict them.

Taking a deal can be tempting for someone who's facing a possible return to jail, says McMunigal. But he adds of Alford pleas, "A lot of people think it's bad. Because if a guy is going to be…punished by the government, then somebody ought to establish that he committed the crime. Either a jury—or he should admit it."

The plea made Peterson a convicted felon, but with credit for the time he'd served in prison, he was able to leave the courtroom.

According to Hello Magazine, as of 2022, Peterson is living in Durham, North Carolina in a ground-floor condo. His defense attorney David Rudolf said in a statement, the home has "no stairs."

Kathleen's family continues to believe Peterson killed her. In particular, her sister Candace Zamperini has been vocal about her belief that Michael Peterson killed her sister.

In an interview with a BBC Radio podcast she said, "Many times during the trial, something would happen, and I would want to tell Kathleen... And then, oh that’s right, she’s dead. 'Oh that's right—it's you, Kathleen, whose murder we're talking about.' It was like constantly a bucket of cold water in my face. I still have a hard time… My sister is the story here; she is the murder victim."

Further inquiry into what happened to Kathleen is stymied by Peterson's plea deal.

"Once he said…’I'm willing to accept a conviction,’” says McMunigal, “basically it's over."