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

Betty Miller, 70, 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 in Shelburne, according to a criminal complaint filed in federal court on Thursday.

Police were called to Wake Robin on Tuesday after Miller told healthcare providers she had manufactured the ricin and placed it on other residents' food and beverages, the agent said in the complaint. No residents reported symptoms of ricin poisoning, he said.

The FBI and the Vermont Department of Health interviewed Miller on Tuesday evening at the University of Vermont Medical Center, federal law enforcement authorities said in a statement.

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In a statement Friday, Wake Robin President and CEO Patrick McKee said the affected apartment had been closed off and searched.

"We have received assurances from the VT Department of Health and the FBI that no one’s health is at risk," McKee said in the statement. "The resident of the apartment in question is now involved with the criminal justice system and will not be returning to Wake Robin."

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 made her first appearance in federal court in Vermont on Friday. Judge John Conroy noted her mental health history. He did not elaborate.

Miller was placed in custody and is scheduled to be in court again on Wednesday. She was represented on Friday by a federal public defender, according to the U.S. Attorney's Office and the FBI. She said she was working on getting a lawyer.

If convicted of the charge of unregistered possession of ricin, Miller could face up to five years in prison, according to federal law enforcement authorities.

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 amid 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.