A sign marks the entrance to the Wake Robin retirement community, Wednesday, Nov. 29, 2017, in Shelburne, Vt. Vermont State Police and FBI said they were investigating the source of the deadly toxin ricin that was found at the retirement community. A Wake Robin spokeswoman said residents were safe. (AP Photo/Lisa Rathke)

BURLINGTON, Vt. - A retirement community resident made ricin and tested the deadly toxin on her neighbours by putting it on their food or in beverages over a period of weeks, investigators said.

Betty Miller told an FBI agent that she wanted to "injure herself" and was testing the poison's effectiveness on other residents at the Wake Robin senior living facility, according to a criminal complaint.

A handcuffed Miller, 70, made her first appearance in federal court Friday. Judge John Conroy noted that Miller had a "lengthy mental health history," but did not elaborate.

Miller was placed in custody and was scheduled to be in court again on Wednesday. She said she was working on getting a lawyer.

Police were called to the senior community in Shelburne on Tuesday after Miller told heath care providers she had manufactured the ricin and placed it on other residents' food and beverages, the agent said in the complaint.

The Health Department said Friday that it became aware of one person who likely became ill with ricin poisoning but said no one is currently ill with ricin poisoning.

Miller said she harvested 30 to 40 castor beans from plants growing on Wake Robin's property and made 2 to 3 tablespoons of ricin twice in her kitchen, the complaint said. She exposed other residents to the ricin on at least three occasions, the complaint said.

Investigators found a pill bottle half full with powder labeled as ricin in a basket in a kitchen cabinet of Miller's apartment a midst other pill bottles labeled "apple seed," ''cherry seed" and "yew seed," the complaint said.

The powder tested positive for ricin. Investigators also found instructions for making ricin that apparently were from the internet, the affidavit said.

If inhaled, ricin causes difficulty breathing and other symptoms. If ingested, symptoms include vomiting, diarrhea, hallucinations and seizures. Initial symptoms of ricin poisoning are most likely to occur within four to 10 hours of exposure.

Wake Robin said in a statement Friday that one apartment was closed off and that the resident living there will not return.

"We have received assurances from the Vermont Department of Health and the FBI that no one's health is at risk," it said.

News from © The Associated Press, 2017