The official who described the arrest was not authorized to publicly discuss a case that has not yet been made public and spoke on the condition of anonymity. The arrest took place Thursday morning, and the suspect is a man, the official said. No other details were immediately available, including the charges the man might face.

In the absence of harder evidence, Republican lawmakers and right-wing media outlets promoted conspiracy theories about the pipe bombs. House Republicans also criticized security lapses, questioning how law enforcement failed to detect the bombs for 17 hours. Dan Bongino, the current FBI deputy director, floated the possibility last year before being tapped for his job that the act was an “inside job” and involved a “massive cover-up.”

But since arriving at the FBI in March, he has sought to deliver action to a restive base on the far right by promising that the pipe bombs investigation would be a top priority and defending the bureau’s work.