Almost $1 billion worth of Bitcoin that likely originated from Silk Road is on the move, according to blockchain tracker Elliptic.

Some 69,369 Bitcoins have been moved out of a wallet that may be associated with the website, Elliptic said. Silk Road peddled everything from drugs to murder-for-hire before being busted by U.S. agents in 2013. Some Bitcoins associated with the site have been sold in government auctions in prior years.

Whether the $1 billion of Bitcoin is being moved by Silk Road’s owner, law enforcement or a vendor is unclear, according to Tom Robinson, co-founder of Elliptic. The account from which the funds moved is the world’s fourth-richest Bitcoin address, according to BitInfoCharts.

“I’d say I’m about 60% confident that these funds are from the Silk Road at the moment -- I’m not certain about it,” Robinson said in an email.

Bitcoin remains near its highest levels since January 2018, holding above $13,000 since Friday.

Silk Road used Bitcoins to generate the equivalent of $1.2 billion in illicit sales and reap $80 million in commissions in less than three years, according to court documents. Ross William Ulbricht operated the Silk Road from January 2011 until it was shut down.

“Why the sudden move of funds?” Robinson said in a Tweet today. “A copy of the encrypted wallet file is reportedly being circulated -- if someone cracked the password they could seize the Bitcoins. The owner of the wallet has perhaps moved the BTC to a new wallet to prevent this.”