Federal prosecutors charged a Burlington woman with mailing a threatening letter containing a white powder to the Bangor home of Sen. Susan Collins.

Suzanne E. Muscara, 37, faces one count of mailing a threatening communication, and faces up to 10 years in prison and a $250,000 fine if convicted. She was scheduled to make her first appearance in U.S. District Court in Bangor on Monday.

The charge arose from an investigation last year after Collins’ husband, Thomas Daffron, opened a different letter at their home Oct. 15 that purported to be coated in the poison ricin, according to the office of U.S. Attorney Halsey B. Frank.

An affidavit filed in federal court by FBI agent Michel J. Verhar describes how, as a result of the police response to the first threatening mailing, a U.S. postal inspector began hand screening all mail sent to Collins’ home.

On Oct. 17, two days after the first letter was discovered, the postal inspector found a letter addressed to “Susan Collins or current resident” that began to leak a white powder, Vehar wrote.

Inside was a double-sided Aetna Medicare Solutions flier, with blue handwriting on one side: “AnthRAX!!! HA HA HA!!!” Near the writing was a stick figure drawn with Xs for eyes, the tongue sticking out, and with “You” and an arrow pointing to the stick figure’s face, according to affidavit.

After determining that the second letter contained starch powder and that the contents were not toxic or poisonous, the envelope was evaluated by FBI agents, who found a partial fingerprint on it.

Muscara had been previously arrested in Pennsylvania on an unspecified charge, so her fingerprints were submitted to a national database that FBI agents used to check for matches with the partial print from the envelope. Muscara’s was a match.

Agents found she had a current Maine driver’s license listing an address in Burlington, in Penobscot County.

During an interview, Muscara admitted sending the powder, said it was not poison, and recalled including a note that included the word “anthrax,” according to the affidavit.

“Muscara told us that she thought the letter would be intercepted by law enforcement before it reached Senator Collins and did not believe the note would be taken seriously.”

The threats came during and after the tense buildup to Collins’ pivotal vote  in support of Supreme Court nominee Brett Kavanaugh, who had been accused by multiple women of sexual misconduct during his high school and college years.

Kavanaugh angrily denied the allegations, and pressure mounted on Collins from both sides to either support or reject the nominee. Protesters swamped her offices in Portland and Washington, D.C., and dozens were arrested during demonstrations in the nation’s capital.

“Sen. Collins and Mr. Daffron greatly appreciate the extraordinary efforts made by state and federal law enforcement agencies which culminated in an arrest in this case,” Annie Clark, a spokesperson for Collins, said in a statement Monday.

No arrests have been announced in connection with the first letter sent to Collins.