They’re called “phreakers,” and they can do with a phone what hackers can do with computers. Few were more skilled—or more feared—than Matt Weigman, a blind teenager from East Boston. Using his heightened senses, he made himself untouchable. What he lacked, the FBI says, was the good sense to know when to hang up.

Plenty of phreakers experience that moment when the wall between life on the phone and its real-world consequences comes crashing down. For Bill Acker, it happened when he was 18 and was visited by a New York Telephone Company investigator, who had a few questions about some free calls being placed by a student at the Lavelle School for the Blind. Chris Bernay was 15 when the cops showed up. He’d been monkeying with 9-1-1 calls.

Matt Weigman had his moment in December 2006, when FBI agent Lynd, a 40-year-old West Point grad and Desert Storm veteran, knocked on the door at Weigman’s apartment in East Boston. Lynd had served nearly a decade on the agency’s cybersquad unit, helping at one point to collar a gang of hackers who were notorious for breaking into government computer systems and had once defaced the White House website. Lynd discovered that the SWATting hoaxes were more ubiquitous than he’d first imagined; ultimately he uncovered more than 200 incidents that had tangled up law enforcement officials in more than 40 jurisdictions in at least 10 states.

What’s more, he’d discovered a kind of Ocean’s Eleven–esque cast of misanthropes behind it all. There was the Financier, Chad Ward from Syracuse, New York, who would pay the crew to carry out the SWATtings on party-line foes. The Researcher, Jason Trowbridge from Houston, who would track down the target’s information. The Voice, Guadalupe Martinez from the Seattle area, who would place the menacing 9-1-1 calls. And then there was Weigman, whom Lynd later described in an affidavit as the “individual responsible for altering telephone services in furtherance of this scheme.” The Phreaker. Lynd would not comment for this article because the case against Weigman is pending. But in documents to be presented at his trial this month, Weigman is accused of being the person behind the effort to mask the origins of the calls—a master phreaker, caught using cheap phone tricks.

As Lynd interviewed Weigman, who was still just 16, the boy’s mom sat nearby. While they talked, Lynd’s cell phone rang. As the agent took the call, Weigman listened closely, trying to pick up the voice on the other end. Almost instantly he recognized it as belonging to a Verizon fraud investigator named Billy Smith, with whom he’d had run-ins before. After Lynd hung up, Weigman asked if Smith was assisting in the FBI investigation. Of course, he already knew the answer.

A month after Lynd’s visit to East Boston, the Voice was arrested. The Financier and the Researcher went down six months later, along with Stuart Rosoff. Last May they all went to prison, some for as many as five years. Because federal prosecutors rarely bring cases against minors, Weigman was spared.

To anyone paying attention, the message was clear: The game was over. This was a good time to get off the party line. To lay low. And maybe Weigman wanted to. Things had been different since he’d been getting serious with Chastity. Everyone on the party line said so. He was calmer, less angry, it seemed. He was telling friends that he was thinking about college.

But Weigman couldn’t stop, according to Lynd’s affidavit in the government’s case against him. Maybe it was curiosity, or maybe fear, but he was convinced the federal investigators were still building a case against him. Relying on the skills that had made him untouchable on the party line, according to Lynd’s affidavit, Weigman set about trying to break into the voice mail of the U.S. Attorney’s Office in Dallas. Lynd claims Weigman called party-liner witnesses and attempted to intimidate them, pressing them to stop cooperating with the FBI. Lynd also contends in an affidavit that Weigman threatened to kill potential witnesses and their family members, even intimating he might harm one woman’s baby.

To make matters worse, in late spring Billy Smith, the Verizon fraud investigator, disconnected a phony account Weigman was using to make calls. It was infuriating enough that Smith was working against him by aiding the FBI, but this new affront crossed a line for Weigman.

According to Lynd’s affidavit, after posing as a Verizon employee to get his phone turned back on, Weigman retaliated, obtaining Smith’s personal telephone billing records and placing a number of harassing calls to his house.

When Weigman’s phone was blocked from calling certain numbers, he suspected Smith (who declined to comment for this story) was behind it. It was more than Weigman could handle. His girlfriend, his community, his whole life—it all required unfettered access to a dial tone. Weigman decided the only way to resolve the situation would be to pay a personal visit to Billy Smith at his home in New Hampshire.