Updated

A 70-year-old woman accused of manufacturing the deadly toxin ricin and testing it on fellow residents at a Vermont retirement community has pleaded not guilty.

The Burlington Free Press reports that Betty Miller was arraigned on Friday.

Miller, who has an extensive mental health history, was arrested last month after telling investigators she made the ricin at her home at the Wake Robin community in Shelburne because she wanted to "injure herself." According to a federal complaint, she told investigators she tested the poison's effectiveness by putting it in residents' food or beverages. No one became seriously ill.

According to the complaint, she said she made the ricin from castor beans she harvested from plants growing at Wake Robin.

Miller is being held in a Vermont jail.

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Information from: The Burlington Free Press, http://www.burlingtonfreepress.com