A couple from New York has been accused with conspiring to launder $4.5 billion in stolen bitcoin funds. In what US Deputy Attorney General Lisa Monaco termed “the department’s largest financial seizure ever,” law enforcement agents seized $3.6 billion of those funds.

Ilya Lichtenstein, 34, and his wife, Heather Morgan, 31, are accused of attempting to launder money obtained from the massive Bitfinex breach in 2016.

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Despite a string of heists from cryptocurrency sites, the arrests and money confiscation are a success for US law enforcement. In attacks on virtual currency exchanges in recent years, hackers have made off with hundreds of millions of dollars at a time.

According to Justice Department officials, Lichtenstein and Morgan have been charged with conspiracy to launder money and conspiracy to defraud the United States, both of which carry a maximum sentence of 20 years in prison. An attorney for the couple could not be reached for comment right away.

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The Justice Department did not announce charges for the actual Bitfinex attack, and officials from the department declined to speak further, citing an ongoing investigation.

As the economic impact of ransomware and other intrusions has expanded, law enforcement agencies have become more aggressive in their pursuit of and seizure of bitcoin used by criminal hackers. Colonial Pipeline paid a Russian-speaking gang $4.4 million in ransom last year, and US officials recovered $2.3 million of it last year.

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“This shows that even when sophisticated money laundering techniques are used, the indelible blockchain records usually allow law enforcement to link criminal activity to individuals,” Tom Robinson, co-founder of cryptocurrency analysis firm Elliptic, told CNN.