Dateline: Dateline: Poison Twist - Everything we know about the latest true crime episode of NBC

The latest episode of NBC’s Dateline titled Poison Twist will follow the case of Mary Yoder, who was poisoned to death in 2015. The show will premiere on the network on March 21, 2025. The Dateline episode will go in-depth into the case that saw the bereaved family looking to uncover the reason behind the death of Mary. Kaitlyn Conley, her son’s former girlfriend and office manager at Mary’s Chiropractic Clinic, was convicted of manslaughter.

The harrowing event took place in Whitesboro, New York on July 20, 2015, and was one of the most talked about cases in the country. The episode will share details of the case that have not been shared before including fresh evidence and interviews with family and investigators.

What happened to Mary Yoder?

A resident of Whitesboro, New York, Mary ran a chiropractic clinic with her husband Bill Yoder. The 60-year-old chiropractor worked with her son Adam and Kaitlyn Conley, Adam’s ex-girlfriend.

Mary was rushed to hospital on July 20, 2015, after she complained of severe stomach pain. However, her condition got worse and she died within 48 hours. After a few weeks, a toxicology report stated that she had colchicine poisoning. It is a medication used to treat gout. Knowing that Mary had never voluntarily taken it, the case turned into a homicide. The investigators suspected that Mary may have been poisoned through the daily protein drink that she consumed at her office every day.

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The suspects in the investigation

According to the autopsy, Mary had been poised with agricultural-grade colchicine, which could have killed her 15 times over. The authorities started investigating everyone close to Mary to uncover the truth.

Mary’s husband who had been dating her sister shortly after her death was first on the radar. However, the police received an anonymous letter sharing that Adam was behind the murder and that he kept the lethal drug called colchicine in his car. Though they discovered it in his car, when they found that the letter was written by his former girlfriend Kaitlyn Conley, everything changed.

Adam and Kaitlyn had a history of conflict. They had initially met at a high school graduation party in 2011. The couple had an on-again, off-again unstable relationship. In 2014, she had even accused him of abuse but the case was dismissed because of lack of evidence.

During the investigation, Kaitlyn’s behavior seemed highly suspicious. Her story had many loopholes and she was unable to correlate the events of the day and her insistence on Adam being a suspect. Later, when Kaitlyn’s work computer was checked, the purchase link to an order of colchicine was found to be linked to her email.

Conviction of Kaitlyn Conley

Kaitlyn Conley was charged with second-degree murder in 2016. During the first trial, the prosecution stated that Kaitlyn committed the crime to seek revenge against Adam. However, the jury was unable to unanimously come to a decision, resulting in a hung jury.

In 2017, the case went for a second trial, and this time she was convicted of the crime with a 23-year prison sentence. Kaitlyn claimed that she was being made a fall person in the case.

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The aftermath of the trial

While Mary’s husband and children firmly believed that Kaitlyn was guilty of first-degree manslaughter, some of Mary’s relatives including her sisters felt that the case was mishandled and Kaitlyn’s conviction should be overturned.

Kaitlyn and her family continue to claim her innocence.

Watch Dateline: Poison Twist on March 21, 2025, on NBC at 9/8c

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