It took less than a day for the FBI to come asking about the new mayor.

On the morning of April 7, a federal agent strolled into the office of Vermont’s secretary of state, wanting information about Bernie Sanders’s past political affiliations. He was carrying out a request by an assistant US attorney in New York, then representing the government in a lawsuit launched by the Socialist Workers Party.

In context, the visit was less sinister than it appeared. Though Sanders had only ever served as an elector for the party, its national secretary had incorrectly identified him on the stand as its candidate. The defense, looking to test the secretary’s credibility as a witness, wanted to verify this. It was, as far as FBI visits went, all pretty benign. The US attorney in Vermont even called Sanders in advance to tell him he wasn’t under investigation.