A second document alleges that private communications recovered from the Silk Road's computer server suggested the suspect had been willing to pursue violent means to defend his interests.
It said that messages sent in March and April indicated he had "solicited a murder-for-hire" of a Canadian Silk Road user nicknamed FriendlyChemist who had tried to extort money by threatening to release the identities of thousands of the site's users.
FBI notice It is no longer possible to access the Silk Road's website
Subsequent messages indicated he had been sent a photograph of the victim after paying $150,000 to have the blackmailer killed.
"I've received the picture and deleted it. Thank you again for your swift action," Mr Ulbricht is alleged to have written to an assassin.
However, the court documents note that Canadian law enforcers have said there was no record of a homicide taking place in White Rock, British Columbia at the time.