A man believed to be a key figure in a ransomware group has been arrested in France over a string of cyberattacks on critical infrastructure across the world, including one in 2020 against Japanese video game maker Capcom Co., police said Friday.

Law enforcement authorities from Japan, the United States and nine European countries cooperated in the investigation targeting the Ragnar Locker group, which threatened to publish and block access to victims' personal data unless ransoms were paid for decryption tools.

Screenshot of a website seized as part of an international law enforcement investigation. (Image courtesy of Japan's National Police Agency) (Kyodo)

The man, suspected of being a developer for the group, was arrested by French authorities in Paris on Monday, Japan's National Police Agency said. He was the "key target" of the international investigation.

In a five-day operation through Friday, searches were conducted in the Czech Republic, Spain and Latvia, according to Europol. While the ransomware's infrastructure was seized in the Netherlands, Germany and Sweden, the associated data leak website was also taken down in Sweden.

The international sweep "delivered a major blow to one of the most dangerous ransomware operations of recent years," Europol said in a press release.

Among Japanese firms attacked by the group, Capcom said in November 2020 that the personal information of customers and clients was stolen in a cyberattack.

A Russian national was charged in the United States in May with ransomware attacks against law enforcement agencies, and Japanese police suspect he was also involved in the attack on Capcom, investigative sources said.

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