Ercan Findikoglu, a Turkish citizen also known by the online nicknames “Segate,” “Predator,” and “Oreon,” pleaded guilty to computer intrusion conspiracy, access device fraud conspiracy, and effecting transactions with unauthorized access devices for his leadership role in organizing and carrying out three cyberattacks between 2011 and 2013 that inflicted more than $55 million in losses in a matter of hours on the global financial system.

The guilty plea took place before United States District Court Judge Kiyo A. Matsumoto. At sentencing he faces 57.5 years of imprisonment.

Findikoglu’s organization used sophisticated intrusion techniques to hack into the systems of credit and debit card processing companies, stole data for prepaid debit cards, and eliminated withdrawal limits for those debit cards.

During these cyber-attacks, Findikoglu and other co-conspirators manipulated network administrator privileges at the victim card processing companies and stole the personal identification numbers (PINs) associated with the compromised debit cards.

They then disseminated the stolen card data worldwide to the leaders of cashing crews and directed that their teams use the information to make fraudulent ATM withdrawals on a massive scale across the globe. As a result of the effective elimination of withdrawal limits, these cyber-attacks were known as “unlimited operations.”

In one operation on February 27 and 28, 2011, Findikoglu’s cashing crews withdrew approximately $10 million through approximately 15,000 fraudulent ATM withdrawals in at least 18 countries. In a second operation on December 22, 2012, Findikoglu’s cashing crews withdrew approximately $5 million through more than 4,500 ATM in approximately 20 countries.

In a third operation on February 19 and 20, 2013, Findikoglu’s cashing crews in 24 countries executed approximately 36,000 transactions and withdrew approximately $40 million from ATMs. During this third operation, in New York City alone, the crews withdrew approximately $2.4 million in nearly 3,000 ATM withdrawals over the course of less than 11 hours.

Findikoglu was paid a significant portion of the illegal proceeds from these unlimited operations.

Findikoglu was arrested in Frankfurt, Germany, in December 2013, and was extradited to the United States in June 2015.

Today’s guilty plea is the latest in a string of convictions of dozens of other members of the cybercrime organization, including members of a New York City cell charged in May 2013 in connection with their roles in two of the attacks.