The "bitcoin" were found in a digital wallet on the computer of Ross Ulbricht, who was arrested Oct. 1 in San Francisco, USA Today reported Friday.
Documents released Friday said federal agents also seized the Silk Road website and accounts of the site's buyers and sellers, plus 29,655 bitcoin with a value of $5.8 million.
Federal agents charge the website was a hub of illegal cyber activity, allowing anonymous transactions in drugs, forged documents and murder-for-hire.
Ulbricht, 29, is charged with money laundering, drug dealing, computer hacking and murder-for-hire.
Silk Road transactions used only bitcoin, which are not controlled by any central banking authority and can be used only in the digital world. The accounting system used by the website disguised the users. Silk Road collected a commission on each transaction.
On Friday, a bitcoin was valued at $197.57.
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