Trump said the pardon was “full and unconditional.” He said he called Ulbricht’s mother to break the news to her on Tuesday local time. Ulbricht has been imprisoned at a federal prison in Arizona and it was unclear when he would be released.

Prosecutors said some people died due to drugs bought on Silk Road.

What was Silk Road and how did it work?

Those steps, they said, included soliciting the murders of several people who posed a threat, though they also said no evidence exists that any murders were actually carried out.

Members of the US Libertarian Party stood on chairs while chanting and demanding the release of Ross Ulbricht during the party’s national convention in May last year. Source: Getty / Chip Somodevilla

Ulbricht acknowledged he created Silk Road, which a defence lawyer at his trial said was intended as a “freewheeling, free market site.” But his lawyers contended Ulbricht had later handed off the website to others and was lured back toward its end to become the “fall guy” for its true operators.

A federal jury in Manhattan in February 2015 found Ulbricht guilty of charges including distributing drugs through the internet and conspiring to commit computer hacking and money laundering.