A New York couple accused of laundering $4.5 billion in cryptocurrency tied to the 2016 hack of digital currency exchange Bitfinex are still negotiating a possible plea deal while reviewing more than 1.1 gigabytes of evidence in the case, prosecutors said.

Ilya "Dutch" Lichtenstein, 34, and his wife, Heather Morgan, 32, the self-proclaimed "Crocodile of Wall Street," were due to appear in a federal court in Washington this coming Friday.

But in a court filing on Monday, U.S. Memorial Day, federal prosecutors asked to postpone the hearing until Aug. 2, citing "discussions regarding possible resolutions of the case short of trial" and the need for the defendants to review "voluminous financial records" turned over by the government.

Lichtenstein and Morgan were arrested in February and accused in a criminal complaint of conspiring to launder 119,754 bitcoin stolen after a hacker in 2016 broke into Bitfinex and initiated more than 2,000 unauthorized transactions.

U.S. Justice Department officials said the transactions at the time were valued at $71 million in bitcoin, but with the rise in the currency's value, the value reached $4.5 billion at the time of their arrest.

The couple had active public profiles, with Morgan known as rap singer "Razzlekhan," a pseudonym that she said on her website referred to Genghis Khan "but with more pizzazz."

A grand jury has yet to return an indictment against the pair, after prosecutors first signaled in March they had agreed to pause the Speedy Trial Act in order to discuss a possible plea deal.

Lichtenstein is being held in jail without bond, while Morgan was released to house arrest.

(Reporting by Sarah N. Lynch; Editing by Howard Goller)