George Trepal became the primary suspect in the thallium poisoning death of Peggy Carr after giving police his theory of why someone would want to poison the Pye Carr family. By saying the killer probably wanted the family to move, he echoed the sentiment in an anonymous note the Carrs received several months before they consumed the tainted Coca-Cola, which also left Peggy Carr’s son and stepson gravely ill.
Authorities investigating Trepal’s past found that he had not only studied chemistry in school, but put that education to use by leading a massive methamphetamine ring in the 1970s. This fit with the police profile of the poisoner, who analysts said had to have extensive knowledge of chemicals to choose a form of thallium that would not alter the taste, appearance, or carbonation of the Coke. It took FBI chemists over a month of testing with various forms of thallium to find a type – thallium nitrate – that was undetectable to the eye.
In addition to possessing knowledge of chemicals, Trepal also was an extremely smart man who belonged to MENSA, a society of individuals with high IQs. Trepal and his wife Diana Carr (no relation to the Pye Carr family) often hosted murder mystery weekends for fellow MENSA members. Police took advantage of one such event to introduce Special Agent Susan Goreck into Trepal’s life in the undercover role of Sherry Guin.
Goreck expressed interest in Trepal’s home, which he had by then put up for sale. She explained that she was in the midst of a divorce, which her lawyer husband made unpleasant by using his connections to unfairly sway the proceedings. During her viewing of the house, she feigned great interest in Trepal’s stories and an admiration for his intelligence, steps designed to increase his confidence and get him to lower his guard around her. Over the next few months, she met with George several times, accompanied on various visits by fellow agents playing the parts of her cousin and soon-to-be ex-husband.
Finally, Goreck arranged to rent the home from Trepal, as her legal residence would preclude the need for a search warrant, allowing authorities to scour the property for any sign of thallium or other incriminating evidence. The first search of the home turned up several chemical bottles in the shed. The containers were swabbed and the swabs sent off for testing. While waiting for the results, Goreck turned up the heat on Trepal.
Still posing as Sherry Guin, she called Trepal and arranged a meeting with him at McDonald’s. There, she informed him that she had heard about the Carr poisoning and that police had been to the home questioning her about him. While Trepal confessed nothing, he was visibly worried and advised Goreck not to talk to the police.
Two months after the McDonald’s meeting, the lab results were in. A container in Trepal’s shed tested positive for thallium nitrate. Armed with this evidence, police arrested George Trepal for the murder of Peggy Carr.