There was strange trouble at Glen Park Library on the first of October, an otherwise unremarkable Tuesday, in what's otherwise one of the quietest buildings in San Francisco. Around 3 p.m., a librarian heard a thump in the science fiction department. Thinking someone had fallen out of a chair, she went to investigate and saw two patrons holding a spindly young man against a window. One of them, a woman with unusually "beefy" arms, flashed a badge. "FBI," the woman said.

The man at the window, 29-year-old Ross Ulbricht, had a narrow, square-jawed face, copper-colored eyes, and the kind of haircut you'd see on children in Norman Rockwell paintings. He looked pliant and unassuming. He would turn out to be an international drug trafficking suspect. His arrest was two years in the making.

Once a promising engineer, Ulbricht faces a minimum 10-year sentence for allegedly creating Silk Road, a massive drug and contraband marketplace that occupied a dark hinterland of the Internet called the "deep web." He's an accused crime boss whose virtual hideout couldn't be accessed on traditional browsers, and who trafficked exclusively in the electronic currency Bitcoin (a form of money transferred over the Internet, with no central bank attached). Federal prosecutors say he built an empire out of things he couldn't see or touch. His alleged henchmen were doughy computer guys who shipped massive quantities of drugs from their bedrooms. They corresponded over message boards. It's doubtful that Ulbricht met any of them in real life.

To many, Ulbricht seems like a perfect parable for the Internet age, a computer geek who moved drug shipments while pecking at his keyboard. His alleged alias, Dread Pirate Roberts, referred to a series of characters in the novel and film versions of The Princess Bride who were all anonymous and replicable. If he was, indeed, the person cited in court complaints, then he'd taken the idea of a criminal dynasty and rendered it a meme.

But Silk Road might also be the inevitable byproduct of tech culture in San Francisco, where innovation and the desire for personal freedoms are at once an economic engine, a lifestyle, and a belief system. And Ulbricht, the alleged mastermind, left a trail of ideological crumbs to explain his motivations. In college he joined campus libertarian groups and supported Ron Paul's 2008 presidential bid; afterward he moved to San Francisco, tried to partake of the start-up boom. In the interim he wrote long Facebook soliloquies about freedom and personal liberties.

His political philosophy matches a current of thought that is ascendant in Silicon Valley. Look no further than Berkeley entrepreneur Patri Friedman, who amassed more than $2 million in venture capital to build a floating libertarian island just outside the San Francisco Bay. Or San Francisco entrepreneur Balaji Srinivasan, who recently preached secessionism — the formation of a separate society, with unregulated digital currency, and sharing economy hotels, and unlicensed firearms — to a roomful of aspiring start-up founders.

So it was inevitable that, in the land of chaotic, multi-billion dollar IPOs, someone would also build a new version of an ancient economy, dealing exclusively in the forbidden. Dread Pirate Roberts was not the first person to trade in Bitcoin, or to build a site on the deep web, but he caused both of them to snowball in popularity. By disrupting the black market, he'd taken all of San Francisco's ideals about tearing down institutions to their extreme. He inspired a confederation of supporters whose faith in Silk Road has an almost evangelical cast.

But they were enchanted by the vessel, not the person — or people — behind it. Dread Pirate Roberts, however many of them there may be, was just an avatar; Silk Road fulfilled the dark promise of San Francisco's tech culture.

The small cult of adoration Ulbricht himself spawned, via a few "Free Ross Ulbricht" Facebook pages, didn't bear any trace of old-school outlaw allure. If anything, fans seem fixated on the ideological underpinnings of Silk Road, rather than the man who prosecutors say embodies them.

And Dread Pirate Roberts never resisted being a cipher for a set of ideals. Many observers say the avatar is no accident; that the founder of Silk Road saw himself as a franchise rather than a Don. Some even believe the name extends to multiple administrators, most of whom may never be caught. Their suspicions were supported when a new iteration of the site, Silk Road 2.0, arose with the same template, the same product offerings, and a new Dread Pirate Roberts just weeks after Ulbricht was apprehended.

If Ulbricht was endlessly franchisable online, he was equally replaceable in real life, a boy-next-door type with a willowy frame and nondescript features, and a lifestyle that resembled that of any bright-eyed, aspiring San Francisco tech bro. Even while harvesting millions in Bitcoin, Ulbricht lived modestly, on a tight-knit row of single-family walk-ups whose owners say they had no idea that an alleged drug dealer operated in their midst. A barista at Momi Toby's Revolution Cafe & Art Bar in Hayes Valley, cited in the FBI indictment as a place where Ulbricht worked, says he can't recall seeing Ulbricht's face, either.

When pressed, the barista bunches his mouth studiously. "Crime bosses used to be exciting," he says. "Like, you know, Al Capone."

This invisibility worked in Ulbricht's favor for a while.

The search for Dread Pirate Roberts took two years and spanned continents, as federal investigators pierced through a web of aliases and encryptions that Silk Road's operator used to shield himself. FBI special agent Christopher Tarbell says in a sworn affidavit that he and other law enforcement began purchasing drugs on the site in November 2011, about 10 months after Silk Road's inception.

At that point, the site's portal was a black screen with prompts for a username and password, and a button directing users to "click here and join." It was only accessible via "The Onion Router" (TOR), an Internet network that obscures the locations of computer accessing or hosting websites. When coupled with Silk Road's mandatory use of Bitcoin, that double-layer of insulation served as a portcullis to protect what Tarbell called "a sprawling black market bazaar." He dubbed it "the most sophisticated and extensive criminal marketplace on the Internet today."