Plot summary
Goran and Eames are called in to investigate an anonymous call from a hospital about three alleged murders. Goren detects cyanide poisoning and initially suspects Colleen Braxton (Susan Bruce), a nurse who fits the typical criminal profile of an angel of death but instead she exhibits Munchausen syndrome. The poisonings continue while Braxton is in custody and the source of the cyanide is tracked down to a batch of laced over-the-counter Necedrol pills. The investigation turns to the victims' families which leads the detectives to a widow named Trudy Pomeranski ( J. Smith-Cameron ).
The detectives suspect she killed her husband with cyanide and then laced other boxes of Necedrol around the city in an attempt to cover-up the murder and strengthen her lawsuit against the medical company. In order to catch Pomeranski, Goren encourages ADA Carver to indict Pomeranski's elderly mother for the murders and have detectives Ed Green ( Jesse L. Martin ) and Lennie Briscoe ( Jerry Orbach ) from the 27th Precinct to leak information about the case. This provokes Pomeranski into mailing a cyanide laced letter to the Ledger newspaper in order to clear her mother. However, she is surveilled and subsequently arrested for the murders.
Credits
Adapted from Wikipedia contributors, Law & Order: Criminal Intent season 1. HTML formatting and reference markers removed.