An alleged fraudster dubbed The Crocodile of Wall Street over claims she laundered $4.5 billion in Bitcoin has been freed on bail  - but her husband has been ordered to stay in jail.  

Heather Morgan was freed by a New York City judge Monday, pending trial by a federal court.

But her husband Ilya Lichtenstein remains behind bars due to prosecutors' fears that he could seek immunity in Russia, where he is also a citizen.

Judge Beryl Howell said on Monday that 31-year-old Morgan, referred as 'Razzlekahn' due to her rapping background, was no longer held in custody after the government deemed that she wasn't as involved in the planning of the alleged crimes as her 34-year-ld husband, Ilya Lichtenstein, who was largely in control of the funds. 

The judge also considered Morgan's health issues as a factor, after she had recently had surgery to remove a lump in her breast.

With follow-up appointments expected, she will be closely monitored with an ankle bracelet GPS monitor while she is under house arrest. 

Morgan has also been given restrictions on computer use, and a ban on carrying out cryptocurrency transactions. 

The defense told the court that both defendants would guarantee to appear for all remaining court dates, and pointed out that both of their families, who were in court, were willing to bet their homes on it.

However, Howell finally ruled that there would be a significant 'flight risk' for Lichtenstein and agreed with federal prosecutors who insisted that just a portion of the millions in cryptocurrency that the couple stole could buy a new house or 'buy each of their parents a private island.' 

The judge also shared her concerns that Lichtenstein, who is a dual citizen of the United States and Russia, could seek refuge in a eastern European country, where he could possibly be granted immunity.

Federal prosecutors also revealed that Lichtenstein had a file on his computer titled 'passport ideas,' which included several darknet market links vendors that sell passports, bank cards and other forms of identification. 

The New York couple was arrested earlier in February after they conspired to launder cryptocurrency that was stolen during the 2016 hack of Bitfinex, a virtual currency exchange platform, and currently estimated at $4.5 billion. 

Both are accused of using several techniques to launder Bitcoin, including using fake identifies to create accounts; coding computer programs to execute fast, automated transactions; depositing stolen funds in several accounts across one crypto exchange to cover their previous transactions; converting Bitcoin to other forms of cryptocurrency; and creating U.S.-based business accounts to wire their funds and make them seem legitimate. 

Over five years, dark market onion a hacker allegedly laundered 119,754 bitcoin through 2,000 transactions on Bitfinex's website before transferring the crypto funds into Lichtenstein's digital wallet. 

The couple could face up to 25 years years behind bars if found guilty. 

Bitfinex is a cryptocurrency exchange registered in the British Virgin Islands.

In August 2016, hackers were able to breach its security firewall before stealing about 120,000 bitcoin from its customers.

The amount that was stolen was worth roughly $70 million at the time, when the price of bitcoin was around $600.

At the time, Bitfinex announced to its customers that they would lose 36 percent of their funds to compensate for the losses from the incident.

It also created special digital tokens that were able to keep track of customers' losses. 

Some of the tokens could exchanged for darknet market markets shares of iFinex, the company that operates Bitfinex, while other tokens could be redeemed if the stolen bitcoins were recovered in the future.

The US Department of Justice announced that it would create a special judicial process for victims of the hack to reclaim their losses.

The hackers have never been identified. 

Morgan and Lichtenstein were arrested by federal prosecutors of laundering the bitcoin stolen from Bitfinex, but they are not being accused for actually stealing the bitcoin in the hack.

Authorities were able to recover $3.6B after seizing couple's private keys to digital wallets after their arrest earlier this month.