A hacker who hijacked hundreds of PCs to create a botnet has been sentenced to 41 months in jail by a US court.
Robert Matthew Bentley of Panama City, Florida also faces $65,000 (£33,000) in fines and will be under supervision for three years on his release.
The hijacked PCs were used to attack other computers and install programs that plagued users with pop-up adverts.
He was caught following an investigation by the Metropolitan Police's Computer Crime Unit (CCU).
The investigation began in December 2006 after marketing firm Newell Rubbermaid notified the CCU about an intrusion on its network.
The trail led the investigators to Florida where Mr Bentley was using computers to co-ordinate attacks.
He and his accomplices drove so much data through the hijacked Rubbermaid machines that it almost brought the firm's network to a halt. The damage cost $150,000 (£77,000) to put right.
Aiding the investigation were the US Secret Service, FBI, security firm Sophos and other law enforcement agencies.
A botnet is a collection of computers under the remote control of a malicious hacker who then uses them for their own purposes. Most spam or junk e-mail is thought to be routed through hijacked PCs.
The hacking team were paid for every machine on which they successfully installed the ad-serving software and, according to US Department of Justice, made thousands of dollars out of their series of attacks.
"These computer criminals have no qualms about infecting computers around the world and causing thousands of pounds of damages," said Bob Burls, from the Metropolitan Police Computer Crime Unit in a statement.
"In their greed, they cause devastating damage to both private and company computers."