Prosecutors called to the witness stand on Wednesday morning a 40-year-old man from Orange County, New York who, at one time, made $60,000 to $70,000 a month selling heroin on the anonymous online marketplace Silk Road.

The goal was not to prove that Ross Ulbricht, who is on trial for allegedly being the mastermind of the illicit drugs marketplace, is the man behind the pseudonym Dread Pirate Roberts. By calling on Michael Duch to testify, prosecutors wanted to show the jury a grim picture of how Silk Road fueled the addictions of desperate drug addicts and how easy it was for them to obtain illegal substances via the website's private network.

Donning a dark blue prisoner's suit, Duch described to the jury how he was able to sell a total of 31,826 0.1 gram bags of heroin, or just about 3.18 kilograms of the illicit substance, by connecting with "sickdope" customers on Silk Road. Duch, who was arrested just as he was about to mail a package of heroin at the post office of Monroe, New York in October 2013, the same month Silk Road's operations were shut down and Ulbricht was arrested in San Francisco, is cooperating with authorities in an attempt to reduce what would normally be a minimum of 20 years in prison for high-volume narcotics trafficking.

Initially, Duch went on Silk Road in 2012 after he heard about it in a news TV program. By that time, he was well into a five-year addiction for painkillers after a doctor prescribed it to him for a sports injury sustained in 2007. But Duch's addiction was increasingly becoming financially unmanageable, as he was making only $75,000-a-year for his work as an individual computer consultant, a figure not enough to sustain his $3,000-a-month addiction. That was when he decided to peddle the drugs himself.

"I had an addiction," an obviously pained Duch told the jury. "I needed to feed it."

Seeing how the "relative ease" offered by Silk Road could let him "potentially get away with it," Duch began peddling drugs online under the username Deezletime. He purchased bags of heroin from a street-level dealer, who sold it to him for $3 apiece or $349 for each 50-bag "brick," and sold it with a 100 percent mark-up to customers who paid through bitcoin, the electronic currency required by Silk Road.

Indeed, it was relatively easy for Duch to attract customers even for the price he offered because many of his anonymous customers were from areas that had no local supply of heroin. He estimates that he was able to sell some 400 to 600 bags of the substance every day, fulfilling more than 2,400 orders.

Duch's main selling point, he said, was the same-day shipping he provided. Duch would place the drugs in moisture barrier bags inserted into nondescript mailing envelopes to avoid drug-sniffing canines and ward off suspicion and the package would be received by his clients, many of whom were addicts going through withdrawal.

He did not, however, get rich. Duch said he placed part of his five-figure monthly earnings back into his drug dealing activities and another part he used for his own growing addiction.

Prosecuting attorney Serrin Turner showed screenshots of some of the messages sent by clients to Deezletime. One customer hidden by the username Wigglyworm begged Duch to send the package immediately, "otherwise, I'm gonna be sick."

"I just want to check [on the shipment] because I am extremely dopesick and NEED something right now," said another.

"I'm throwing up, the worst of the worst withdrawal symptoms, and plus I have life-destroying pain," another read.

Duch said he received these types of messages every day. Asked how he felt about selling the same drug that had ruined his health, career, and his relationship with his girlfriend, Duch said he felt guilty.

"It was something that bothered me on a daily basis," he said.

Although Duch knew Silk Road was managed by Dread Pirate Roberts, he said he didn't know who he was and did not have any direct contact with him.