The second-in-command of Silk Road 2.0, the successor to the infamous underground drug website of the same name, has been sentenced to eight years in prison and four years of supervised release for his role in the operation.

Brian Farrell, 27, was arrested in January last year after an FBI probe uncovered his IP address linked to the dark web-hosted marketplace. In March 2015 he pleaded guilty to a charge of conspiracy to distribute heroin, cocaine and methamphetamine.

His arrest came at the same time as the trial of Ross Ulbricht, aka Dread Pirate Roberts – founder of the original Silk Road marketplace. Roberts was eventually sentenced to life in prison after being found guilty on a wide range of drug distribution charges.

After the original operation was seized by US law enforcement, a successor quickly appeared in the form of Silk Road 2.0. Like its predecessor, it was only accessible via the Tor browser which helped to keep its customers and drug vendors mostly anonymous.

The website was shut down again following a series of raids in 'Operation Onymous' which targeted a number of underground marketplaces across the globe. By the time it was forced offline, the site was reportedly generating sales of about $8m (£5.5m) a month in bitcoin.

As previously reported, the FBI used a somewhat controversial technique to catch Farrell. After the arrest, it emerged the US government had funded research at Carnegie Mellon University which looked at methods to crack the anonymity provided by Tor. In February this year, court documents finally ended the speculation by confirming the US Department of Defense had not only funded the university research but also subpoenaed its findings to locate Farrell.

In November 2014, federal authorities investigating the Silk Road 2.0 arrested its suspected top administrator Blake Benthall who was using the pseudonym 'Defcon'. Prosecutors described Farrell as an assistant to Benthall, stating that he used the name 'DoctorClu'.

In court documents, filed on 25 May this year, Thomas Woods, assistant United States attorney wrote that Farrell was "not a bit player" in the running of the website. Woods said: "He exercised managerial authority and abused his specialised computer skills and knowledge. As Farrell put it the day of his arrest, 'you're not going to find much of a bigger fish than me'."

In this filing, Woods added the Silk Road 'model' – where websites hosted on the dark web are used to sell drugs for bitcoin – presents "a new threat to public safety and health."

He said: "The website expands the serious drug market to all reaches of the country, and indeed the world. The website reaches those who are too apprehensive to conduct a deal on the street, or those, say in rural areas, who may not have a direct drug supplier. This new frontier is dangerous –and a clear message needs to be sent that those who peddle their poison on the internet – face serious penalties."