A San Francisco man who created the underground drug-selling website Silk Road has been sentenced to life in prison by a judge who cited six deaths from drugs bought on his site and five people he tried to have killed.

Passing sentence in New York, US District Judge Katherine Forrest told 31-year-old Ross Ulbricht he was a criminal even though he did not fit the typical profile - he has two collegiate degrees - and she brushed aside his efforts to characterise the business as merely a big mistake.

"It was a carefully planned life's work. It was your opus," she said. "You are no better a person than any other drug dealer."

Ulbricht stood silently as Forrest announced the sentence, which also included an order to forfeit $184m.

The Silk Road was only accessible on the dark web, a part of the internet that requires the specialist software, originally created by the US government, in order to access it.

Ulbricht's 2013 arrest shut down what prosecutors described as an unprecedented one-stop online shopping centre where the supply of drugs was virtually limitless.

Prosecutors said it enabled nearly 4,000 drug dealers to expand their markets from the pavement to cyberspace, selling drugs on a never-before-seen scale to more than 100,000 buyers in markets stretching from Argentina to Australia, from the US to Ukraine.

The government said in court papers that Ulbricht left a blueprint that others have followed by establishing new "dark markets" in sophisticated spaces of the internet that are hard to trace, where an even broader range of illicit goods are sold than were available on Silk Road.

Forrest said the sentence could show copycats there are "very serious consequences".

Prosecutors had not asked for a life sentence, saying they only wanted substantially more than the 20-year mandatory minimum.

'Captain of the ship'

Ulbricht was convicted in February after being found guilty of charges including distributing drugs through the internet and conspiring to commit computer hacking and money laundering.

Prosecutors, who said Ulbricht operated the site for nearly three years from 2011 until 2013, said he collected $18m in bitcoins through commissions on a website containing thousands of listings under categories like "Cannabis", ''Psychedelics", and "Stimulants."

Notes from the field - Al Jazeera's Kristen Saloomey Ross Ulbricht broke his silence during an emotional sentencing that stood in stark contrast to the trial which was very technical in nature. After hearing from a father whose son overdosed and died from heroine bought on Silk Road, the man formerly known as Dread Pirate Roberts broke down in tears and apologised to the families saying: "I never wanted that to happen." "I wanted to empower people to be able to make choices in their lives, in privacy and anonymity," he said. "I am not the man I was when I created Silk Road. I'm a little wiser, more mature, and humble." Prosecutors argued he didn't do it for ideals, he did it for money and lowered the barriers for drug use. They asked for a sentence well beyond the minimum to send a message and deter other online crimes. Ulbricht's attorney argued in submissions supported by experts that the deaths could not be directly attributed to Silk Road, but one victim was found dead of heroin with his browser open to the web page, the torn open envelope on his side. Identified only as Richard, the father of 25-year-old Brian from Boston said he chafes when he hears Silk Road described as a victimless crime. Follow Kristen Saloomey on Twitter: @KSaloomey

They said he brokered more than one million drug deals worth over $183m while he operated on the site under the alias Dread Pirate Roberts - a reference to the swashbuckling character in "The Princess Bride" film.

The judge said Ulbricht's efforts to arrange the murders of five people he deemed as threats to his business was proof that Silk Road had not become the "world without restrictions, of ultimate freedom" that he claimed he sought.

Ulbricht is also charged in Baltimore federal court in an attempted murder-for-hire scheme.

"You were captain of the ship, Dread Pirate Roberts," Forrest said. "It was a world with laws you created. ... It was a place with a lot of rules. If you broke the rules, you'd have all kinds of things done to you."

Prosecutors cited at least five deaths traced to overdoses from drugs bought on Silk Road, and two parents who lost sons spoke in court.

Before the sentence was announced, a sniffling and apologetic Ulbricht told Forrest he was a changed man who is not greedy or vain by nature.

"I've essentially ruined my life and broken the hearts of every member of my family and my closest friends," he said.

"I'm not a self-centred sociopathic person that was trying to express some inner badness. I do love freedom. It's been devastating to lose it."

His lawyer, Joshua Dratel, promised an appeal, calling the sentence "unreasonable, unjust and unfair".

Outside court, Ulbricht's mother, Lyn, called the war on drugs a failure and said two of the victims in the case died during the four months that authorities investigated but did not shut down the website.

As he left the courtroom, Ulbricht carried with him photographs of those who died as a result of drugs purchased on Silk Road.