The Dateline episode “Poison Twist,” which aired March 21, 2025, revisited the 2015 death of Mary Yoder, a 60-year-old chiropractor from Whitesboro, New York, who was killed with colchicine, a gout medication. Her son’s ex-girlfriend, Kaitlyn Conley, was convicted of first-degree manslaughter in 2017 and sentenced to 23 years. She served about seven years before an appellate court threw out the conviction in January 2025, ruling that her trial lawyer should have challenged the search warrant used on her cell phone. Conley is now free, no one else has been charged, and the killing remains officially unsolved.
How Mary Yoder Died
On July 20, 2015, Yoder became violently ill at Chiropractic Family Care, the practice she co-owned with her husband, Bill. She was hospitalized the next day with severe vomiting, diarrhea, and abdominal pain. Her heart stopped multiple times. She was pronounced dead on July 22.
The initial autopsy found nothing. Dr. Robert Stoppacher, the Onondaga County Chief Medical Examiner, consulted Dr. Jeanna Marraffa at the Upstate New York Poison Center, who recognized the pattern: gastrointestinal collapse, a white blood cell count that spiked and crashed, then cardiac arrest. Samples sent to NMS Labs in Pennsylvania confirmed toxic levels of colchicine, a drug prescribed for gout. Stoppacher concluded it had been ingested orally, and the death was ruled a colchicine poisoning.
The Anonymous Letters
The case might have gone cold. On November 23, 2015, two anonymous letters arrived, one at the Oneida County Sheriff’s Office and one at the medical examiner’s office. Both accused Adam Yoder, Mary’s youngest son, of killing his mother, and both said investigators would find a bottle of colchicine hidden under the passenger seat of his Jeep.
Investigators were suspicious from the first read. As Investigator Mark VanNamee later testified, no real killer drives to the sheriff’s office with the murder weapon in the car. Still, on December 8, 2015, they searched Adam’s Jeep with his consent. Under the passenger seat they found a glass bottle labeled “colchicine,” its packaging, and a receipt tied to a Gmail account, mradamyoder1990.
Adam had been about 300 miles away on Long Island when his mother was poisoned. Attention turned to whoever wrote the letters. Interviews and digital records pointed to Kaitlyn Conley, a receptionist at the Yoders’ practice and Adam’s on-and-off ex-girlfriend. On December 21, 2015, confronted with evidence tying the Gmail account to her IP address, Conley admitted writing the letters. She told detectives Adam had confessed the killing to her in September and that she had stayed silent because she was afraid of him. She denied poisoning Mary.
The Evidence Against Kaitlyn Conley
The case prosecutors built was circumstantial but tight. A prepaid debit card Conley had bought in Adam Yoder’s name carried a serial number that matched the receipt found with the colchicine bottle, tracing the purchase to her through Art Chemicals. A forensic extraction of her phone turned up searches for “poison” and “colchicine” and the login credentials for the mradamyoder1990 email account used to place the order. DNA testing identified her as a “major contributor” on both the vial and its packaging; Adam’s DNA was excluded.
Prosecutor Laurie Lisi told jurors Conley poisoned Mary Yoder hoping to draw Adam back to her, and that the plan “briefly worked” when the two reunited after the death. When Adam broke it off again, according to the prosecution, Conley wrote the anonymous letters to pin the killing on him.
Two Trials, Then a Conviction
A grand jury indicted Conley on June 13, 2016, on charges including second-degree murder, forgery, falsifying business records, and petit larceny. Her first trial in 2017, before Oneida County Judge Michael Dwyer, ended in a hung jury after 24 hours of deliberation. The retrial went forward later that year.
Defense attorney Christopher Pelli argued the wrong person was on trial. He pointed at Bill Yoder, claiming Bill had killed his wife to pursue a relationship with her sister, Kathleen Richmond, and to retire. Pelli called a neighbor, Patricia Keating, who said she had seen Bill and Kathleen in an intimate embrace on Richmond’s porch during the week of July 12, 2015, days before Mary fell ill. He noted that Bill kept a marijuana farm in South Carolina and that colchicine has uses in altering plant genetics. He also flagged that Bill had tried to have Mary cremated the day after she died.
Bill Yoder and Kathleen Richmond both testified their relationship did not turn romantic until mid-September 2015, after Mary’s death. The family itself was split. Mary’s sister Sharon Mills swore in a statement that she believed “William Yoder… is the man that I believe killed my sister.” Another sister, Jeannine King, would later ask the sentencing judge for leniency and say she believed Conley had been wrongfully convicted.
In November 2017, the jury acquitted Conley of second-degree murder but convicted her of first-degree manslaughter. She was sentenced to 23 years in prison.
Why the Conviction Was Overturned
Conley served about seven years at Bedford Hills Correctional Facility. Her appellate attorney, Melissa Swartz, zeroed in on a single failure by trial counsel: Pelli had never challenged the warrant used to search Conley’s phone.
The warrant authorized the sheriff’s office to “seize” the phone and “return it to the court.” It said nothing about examining the contents. Investigators sent the phone to a cybersecurity center and pulled a full memory extraction anyway. Everything they took from it, the search history, the email credentials, the debit card admissions elicited from Conley, went to the jury. At a hearing on her motion to vacate the conviction, Pelli acknowledged that “he should have looked closer at the wording of the warrant.”
On January 31, 2025, the Appellate Division’s Fourth Department in Rochester unanimously reversed the conviction. The court held that the warrant was “facially insufficient” under the Fourth Amendment because it did not “specify the items to be seized by their relation to designated crimes.” Cell phones, the panel wrote, hold “at least as much personal and private information” as a home, and “indiscriminate searches of cell phones cannot be permitted.” Because a suppression motion would likely have succeeded and there was no “strategic or other legitimate explanation” for skipping it, Pelli’s failure amounted to ineffective assistance and was “sufficiently egregious and prejudicial as to compromise her right to a fair trial.”
The court vacated the conviction and dismissed count one of the indictment without prejudice, leaving prosecutors free to seek new charges. In February 2025, an Oneida County judge found no legal cause to keep holding her, and Conley was released.
Where the Case Stands Now
On February 4, 2025, at the hearing on Conley’s release, Supreme Court Justice Bernadette T. Clark sealed the case records under New York’s CPL 160.50, which governs files in criminal cases terminated in a defendant’s favor. Then-DA Todd Carville did not object at the time and later said, “I know I didn’t object, and I apologize.”
That sealing has since blocked the DA’s office from taking the case back to a grand jury. When the sheriff’s office applied to unseal the records in May 2025, citing an “extensive ongoing investigation,” Justice Clark denied the request on June 12, 2025, finding no active assigned investigator and calling the application a “pretext.” She ordered the DA’s office to “cease and desist from any further re-presentment of sealed evidence to the grand jury.” An assistant district attorney had already presented some of the sealed material to a grand jury before the order. The DA’s later appeal was unanimously dismissed by the Fourth Department on June 5, 2026.
As of mid-2026, no one is charged in Mary Yoder’s death. Kaitlyn Conley is free. The cell phone evidence that anchored the first two trials may now be inadmissible, and no new indictment has been reported.