Police will soon set up an investigation headquarters to step up their probe into last month's massive theft of cryptocurrency from virtual currency exchange operator Coincheck Inc., sources close to the matter said Friday.

The Metropolitan Police Department's cybercrime division will assign some 100 investigators to the task on Monday, they said. The investigators will mainly analyze data pertaining to unauthorized access to Coincheck's servers.

On Jan. 26, Coincheck lost NEM coins worth about 58 billion yen ($542.59 million) at the time to hackers. Cybersecurity experts have said the stolen currency was split up and dispersed between several digital addresses.

The police have confirmed that holders of the stolen NEM converted some of it to other virtual currencies through a site on the dark web, which can only be accessed through special software for anonymity, and a few Japanese nationals have offered to exchange their currencies for the NEM.

More than 500 million yen worth of the stolen NEM is believed to have been converted into bitcoin and other cryptocurrencies.

One of the Japanese nationals told the police he exchanged some of his virtual currency called litecoin for the stolen NEM "out of interest," according to the metropolitan police.