(Reuters) - A suspicious letter sent to the Maine home of Republican U.S. Senator Susan Collins had a note saying it contained the deadly poison ricin, the senator’s office said on Tuesday, adding any affected areas had been cleared.

U.S. Senator Susan Collins (R-ME) talks with reporters after announcing that she will vote to confirm Supreme Court nominee nominee judge Brett Kavanaugh in a speech on the Senate floor on Capitol Hill in Washington, U.S., October 5, 2018. REUTERS/Yuri Gripas

No one was harmed in the incident that took place on Monday and Collins’ office did not comment on whether the letter sent to Tom Daffron, the senator’s husband, actually contained ricin.

“Mr. Daffron, their dog, and parts of their home were quarantined while the crime lab undertook an analysis of the premises,” Annie Clark, a spokeswoman for Collins said in a statement, adding that “the incident is the latest in a series of threats against Senator Collins, her loved ones, and her staff.”

Collins was thrust into the national spotlight this month when she became a key vote to confirm Brett Kavanaugh to the U.S. Supreme Court, delivering a major victory to President Donald Trump, who has now locked in a conservative majority on the court.

“The testing of the letter, as well as the investigation into its origins, remain ongoing,” Clark said.

Bangor police referred any questions about the incident to the U.S. Capitol Police, which said it did not comment on ongoing investigations. Officials from the FBI, which is also taking part in the probe, were not available for comment.

Daffron told local TV broadcaster WCSH he saw the letter and the word “ricin” on it. He then alerted authorities.

“She’s been subject to a lot of threats, and obviously it’s scary,” he told the broadcaster.

Ricin is found naturally in castor seeds but it takes a deliberate act to convert it into a biological weapon. Ricin can cause death within 36 to 72 hours from exposure to an amount as small as a pinhead. No known antidote exists.

A U.S. Navy veteran from Utah was charged on Oct. 5 with threatening Trump, Defense Secretary Jim Mattis, the FBI director and an admiral by mailing them letters containing castor beans, from which ricin is derived.

(This version of the story corrects headline to show there was a claim of ricin in letter but no conclusion that letter actually contained it)