"A rapport was established very early on," said Gary Tuggle, the head of Baltimore's DEA office. "He obviously ... had a level of confidence in us and we were able to exploit that."

The operation rumbled on throughout the summer, leading to more arrests, authorities said. Not all of those charges have been made public.

Then, in December of 2012, the undercover agent made a big step. He began griping to Dread Pirate Roberts about the small-fry nature of most deals on Silk Road.

"It really isn't worth it for me to do below ten kilos," the agent wrote, according to a charging document against Ulbricht. Typical listings on the site advertised cocaine and heroin by the gram.

Dread Pirate Roberts offered to help find a buyer and set Green to work canvassing the top dealers on Silk Road, according to court documents in Green's case.

Green, a heavyset 47-year-old man who walks with a cane and used the nickname chronicpain, earned his salary resolving disputes between buyers and sellers. He was also supposed to be sniffing around for potential law enforcement plots.

"Hey, I think we have a buyer for you," Dread Pirate Roberts wrote to the agent a day later. "One of my staff is sending the details."

Over the course of the next month the buyer negotiated terms, eventually agreeing to sell a kilogram of cocaine for $27,000 worth of Bitcoins, according to Green's plea agreement.

But unknown to Dread Pirate Roberts or the undercover agent, Green had gone beyond what his boss requested of him. Green agreed to work as a middleman — and his address was sent to the agent.

On Jan. 17, 2013, an undercover postal inspector delivered the brick to Green's home. It was quiet — though a neighbor recalled an unmarked white van that stood out in the neighborhood — until armed men stormed toward Green's single-story house.

Green was booked at the local jail and released, and agents began examining his computers. Green had access to other Silk Road users' messages and financial accounts — including Dread Pirate Roberts' — according to documents supporting his guilty plea.

Word of Green's arrest got back to Dread Pirate Roberts the next week. He understood that a key member of his empire was in the hands of law enforcement. It's not clear whether Green was actively cooperating — that information is sealed in court records — but Dread Pirate Roberts reached his own conclusion.

"I have to assume he will sing," he wrote later to the undercover agent, according to court documents in Ulbricht's case. The bad cocaine deal didn't disrupt their rapport.

Dread Pirate Roberts asked for help, claiming that Green had also stolen from Silk Road users before his arrest.

"I'd like him beat up, then forced to send the bitcoins he stole back," Dread Pirate Roberts wrote, according to court documents.

Then, the next day, he added: "Can you change the order to execute rather than torture?"

The request caught the agents on the case by surprise, but they agreed on a fee of $80,000 for the job.

"I don't think that we had any sort of premise early on that this guy was involved in that level of violence," Tuggle said.

By this time, Green was working with authorities to stage the plot, according to a statement Green released to reporters.

"The agents took photos as they faked my murder," Green said.