Ross Ulbricht, also known as the Dread Pirate Roberts, paid a doctor $500 (£320) every week to share medical advice with customers of his Silk Road drug dealing website.

Ten days before he is to be sentenced for creating and running the multi-million-dollar website, new evidence presented by his lawyer Joshua Dratel describes Silk Road as "the most responsible such marketplace in history, and consciously and deliberately included recognised harm reduction measures, including access to physician counselling."

Dratel went on to describe Silk Road, which was shut down by the FBI in October 2013, as providing transactions which were "significantly safer than traditional illegal drug purchases and included quality control and accountability features." He said customers were "substantially safer" than those who buy their drugs on the streets.

Found guilty in February 2015, Ulbricht faces up to life in prison for creating and running the website, which earned him millions of dollars in sales commission. The site was located on the dark web, a part of the internet hidden from search engines like Google and which can only be accessed through the Tor web browser, which hides the location of both website servers and their visitors.

Paging DoctorX

Evidence submitted by Dr Fernando Caudevilla, a Spanish physician who was an active member of the Silk Road discussion forums for seven months under the name DoctorX, claims Dread Pirate Roberts (DPR) paid him $500 per week to give advice about harm reduction. Even before he was being paid, Caudevilla spent between two and three hours every day on the forums, sending over 450 messages to help Silk Road users understand the risks of taking drugs.

On being offered payment by DPR, Caudevilla said: "Well...that is very generous from you. For that help I would maintain my thread up to date answering questions in 24-48 hours as a maximum delay and also answer all PM in 24-48 hours maximum." In his declaration to the court, the doctor said: "I thus continued my work on a paid basis from mid-August 2013 through October 2013, when the site was shut down."

The new evidence has come to light after District Judge Katherine Forrest asked both sides of the case to provide evidence related to the government's claims that six drug overdose deaths were a direct result of the Silk Road.

Ulbricht's lawyers said the deaths "should not contribute in any manner" to his sentence. They point to a defence medical expert who found "gaping holes in each death investigation," including one death attributed to Silk Road which was caused by "aspiration pneumonia" in someone who suffered from bronchitis.

Ulbricht was found guilty on all counts, which included narcotics trafficking, computer hacking, money laundering, conspiracy to traffic fraudulent IDs and engaging in continuing criminal enterprise. Ulbricht's lawyers admit he created the website as "an experiment", but continue to deny that he was DPR.

He will be sentenced on 29 May and faces between 20 years and life in prison.