This Friday, March 21, 2025, at 9/8c, Dateline NBC presents “Poison Twist”, a chilling investigation into the 2017 manslaughter conviction of Kaitlyn Conley, who was found guilty of poisoning her ex-boyfriend’s mother, Mary Yoder.

Conley, who had worked as an office manager for Mary’s family chiropractic business, was accused of killing Mary in 2015 by poisoning her with colchicine, a toxic substance. The case captivated the community, as Kaitlyn presented herself as the “Little Miss Innocent” in the courtroom—charming and seemingly harmless—but many believed she was hiding a dark side. After a turbulent relationship with Mary’s son Adam, Conley’s actions and the suspicious circumstances surrounding Mary’s death raised red flags for law enforcement.

Dateline takes an in-depth look at Kaitlyn’s trial, where an anonymous letter she wrote to the police pointing the finger at her ex-boyfriend Adam ultimately led investigators to suspect her. Her behavior during...