For two years, the FBI tracked the elusive founder of Silk Road, an internet site that peddled heroin, ecstasy and every known type of prescription medication.
The manhunt ended with the arrest of an unlikely suspect: Ross William Ulbricht, a 29-year-old former physics student from San Francisco.
Prosecutors on Wednesday described Ulbricht as a criminal mastermind who built an illegal drug empire that they estimated had $1.2 billion in sales over the past three years, earning him $80 million. Silk Road was the drug world's equivalent of eBay, acting as a matchmaker between dealers and buyers worldwide.
Authorities allege that the wrongdoing went far beyond narcotics. The site was also a marketplace for firearms, ammunition and computer hacking services. And Ulbricht was accused in separate complaints of paying for the attempted murders of two business associates who he believed had crossed him.
The arrest underscores the extensive use of the internet by criminals who frequently mimic the legitimate business models of internet retailers. Thousands of drug dealers advertised on Silk Road, and dispatched their products via US mail. The site took a slice of each sale using the Bitcoin online currency.
The person behind Silk Road is ''the modern, electronic version of Walter White in Breaking Bad,' '' said Michael Taylor, a computer science professor at UC San Diego who has followed the case. ''People identify with that hero because he's very smart and innovative. At the same time, we disagree with his con.''
The website required users to install software that concealed their identity and location. That made it difficult for authorities to determine who was behind Silk Road, and helped keep the website going.
The Justice Department filed a criminal complaint accusing Ulbricht of conspiracy to engage in narcotics trafficking, money laundering and computer hacking. Prosecutors in Maryland separately accused Ulbricht of attempted murder for paying $80,000 to have a former employee killed.
Ulbricht, who authorities said was known by his internet moniker ''Dread Pirate Roberts,'' was arrested on Tuesday by FBI agents in San Francisco and the website was shut down. Though not widely known, Silk Road had an avid underground following among the drug crowd. It even has a Wikipedia page.
Silk Road was founded by Ulbricht in January 2011, prosecutors said.
On his Facebook page and in YouTube videos, Ulbricht comes across as a clean-cut hipster fascinated by the internet.
He indicated on the LinkedIn job-networking site that he had graduated from the University of Texas with a bachelor of science degree in physics in 2006. He said he attended graduate school in Pennsylvania.
In an interview, he described a childhood growing up with hippie parents in Austin who refused to let him eat unhealthy food. He said he had dabbled in drinking and drugs.
Ulbricht's alleged online alter-ego, taken from the movie, The Princess Bride, cultivated a larger-than-life persona, aggressively courting publicity.
Ulbricht's arrest cast a shadow over Bitcoin. Bitcoin is a fast-growing virtual money. Critics have said it is frequently used as a currency for illegal transactions.
In court papers, prosecutors allege that Ulbricht attempted to orchestrate two killings this year.
Ulbricht is accused of paying $80,0000 in February in an unsuccessful effort to have a former employee killed for stealing from the company. The hitman was an undercover law enforcement officer.
The Justice Department shut down the Silk Road website and seized Bitcoin with an estimated value of $3.6 million, which it called the largest-ever seizure of the virtual currency.
All this is a far cry from what Ulbricht pictured for his future.
Asked in a YouTube interview what his life might be like 20 years into the future, he said, ''I want to have had a substantial positive impact on the future of humanity.''