The FBI says Betty Miller, 70, of Shelburne, told them she wanted to harm herself, but decided to test the effectiveness of the poison by sprinkling it on the food or in the drinks of other seniors living at Wake Robin.
A man charged in the slayings of two engaged doctors in their Boston luxury condominium is due in court.
Bampumim Teixeira is expected to face a judge in Suffolk Superior Court on Tuesday.
Prosecutors say Teixeira bound and stabbed 38-year-old Dr. Lina Bolanos and 49-year-old Dr. Richard Field in their home in May. They say a carving knife was recovered from the apartment.
Police responding to a report of a man with a gun say they found Teixeira at the scene and believed he pointed or fired a weapon at them. Two officers shot him. Authorities later said he had not fired and a fake gun was found at the scene with a bag filled with Bolanos' jewelry.
Prosecutors say Teixeira had no known personal relationship with the victims.
Teixeira has pleaded not guilty to murder and other charges.
