Story highlights A criminal complaint says the woman was using neighbors to test the potency

She is in custody; attempts to reach her lawyer were unsuccessful

(CNN) The cupboard above the stove in Betty Miller's retirement apartment contained bottles labeled "apple seed," "cherry seed," "castor beans," and "ricin," the FBI says.

The potentially deadly ricin, federal agents allege, was homemade by the 70-year-old to go into the food and drink of her neighbors at a Vermont continuing care retirement community.

Earlier this week, the FBI was asked to come to the Wake Robin life care community in Shelburne, Vermont, to investigate a potentially toxic substance.

When an agent interviewed Miller, she allegedly told him she was making ricin in her home and testing its effectiveness on other residents of Wake Robin.

"On at least three occasions, Miller exposed other residents to the ricin she had produced by placing it on food and/or in beverages she expected them to ingest," Special Agent Mark Emmons wrote in a criminal complaint.

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