Ross Ulbricht, the man convicted of operating the deep web drug emporium Silk Road, has begged a judge to "leave a light at the end of the tunnel" in his sentence, which will be handed down on Friday in a federal courthouse in New York.

After a speedy trial, Ulbricht was convicted in February on charges which include drug trafficking, money laundering and operating a continuing criminal enterprise.

In March, it emerged that two undercover FBI agents had extorted thousands of dollars' worth of Bitcoin from Ulbricht during the course of the investigation.

In its heyday, Silk Road was by far the largest drug emporium on the deep web. Estimates of its traffic ranged from $15m to as much as $50m in transactions every month. Using the cryptocurrency Bitcoin, users could buy practically every kind of drug imaginable, from ecstasy to

Vendors were reviewed by buyers to ensure quality, and the site was only accessible via the Tor encryption service. Drugs constituted most of the goods on sale, but users could also buy erotica, cigarettes and other legal services.