TOKYO —
About 99 percent of the bitcoins that disappeared from a virtual currency transaction system operated by Mt. Gox may have vanished due to fraudulent transactions, not from cyberattacks as the company initially claimed, The Yomiuri Shimbun has learned.
The Metropolitan Police Department has been investigating the case in which about 650,000 bitcoins — worth about $205 million as of Wednesday — went missing from Mt. Gox’s online exchange system, which is currently undergoing bankruptcy proceedings.
Police concluded that about 7,000 bitcoins disappeared due to cyberattacks, only about 1 percent of the total bitcoins missing, according to investigative sources within the MPD.
Thus the remaining 99 percent, or about 643,000 bitcoins, are highly likely to have disappeared after the system was fraudulently operated by an unknown party, according to the sources.
The MPD is currently investigating Mt. Gox, suspecting that an individual familiar with the exchange system may have misappropriated bitcoins belonging to the company’s customers.
According to investigative sources, based on analyses of access records and other materials, police confirmed traces of cyberattacks that made the system believe there were failed remittance operations, prompting total erroneous payments of 7,000 bitcoins. But there were no signs of such cyberattacks on the remaining 643,000 bitcoins.
After the voluntary submission of the server system of the company, MPD investigators restored and analyzed the transaction records on the server.
The investigators found at least two suspicious accounts with balances that continued to grow despite no records of bitcoin purchases, the investigators said.
The balances in clients’ accounts were transferred to these suspicious accounts through system operations. When the affected clients checked their bitcoin balances on the website, the transfers were not displayed.
From these findings, the MPD believes that an unknown party may have repeatedly conducted sales transactions using the bitcoins transferred from clients’ accounts to earn a profit margin. But due to the falling market and other factors, the transactions probably generated massive losses, eventually resulting in the disappearance of clients’ bitcoins, investigators said.
Police believe such fraud could be committed by people familiar with the system, such as those involved in the management of the transaction server. The MPD will therefore question Mt. Gox employees and people related to the firm to examine how the system was managed.
Mt. Gox’s bitcoin transaction website was launched in 2011 by president Mark Karpeles. The site started by the French-born 29-year-old was once a major player in the bitcoin market. But in February, the company filed for court protection under the Civil Rehabilitation Law, claiming that bitcoins disappeared from its system due to cyberattacks. It subsequently descended into bankruptcy.
