SERRAVAL, FRANCE -- A man suspected of involvement in a large-scale online attack against an Internet spam-fighting service has been returned to his native country, the Netherlands, and ordered to remain in custody as an investigation proceeds.
The suspect, Sven Olaf Kamphuis, was transferred to the Netherlands from Spain on Monday after having been arrested at his home in Barcelona last month, according to the Dutch authorities.
On Wednesday, a judge in Rotterdam ordered that Mr. Kamphuis remain in custody for up to two weeks as a police investigation proceeds, said Wim de Bruin, a spokesman for the Dutch national prosecutor's office.
"He is being held on suspicion of participating in DDoS," Mr. de Bruin said, referring to distributed denial of service attacks, a criminal offense under Dutch law.
The attacks slowed Internet service globally for several days in April, especially in Russia and other European countries.
The attacks in question, which crested last month, took aim at the Web site of Spamhaus, a group that provides e-mail services and other clients with lists of suspected spammers.
In March, Spamhaus added two concerns run by Mr. Kamphuis -- a Web hosting service called CyberBunker and an Internet service provider called CB3ROB -- to its blacklist.
Though Mr. Kamphuis has solicited support for action against Spamhaus in postings on Facebook, he has denied participating directly in the attacks.
He has not been charged with any crime.
The Dutch police can hold Mr. Kamphuis for up to two weeks; at that point, with a further court ruling, they could keep him in custody for up to 90 additional days without filing any charges.
This article originally appeared in The New York Times.