In the first case of its kind in the U.S., federal authorities Thursday arrested a California man and charged him with accumulating a botnet of more than 400,000 machines, including some owned by the Department of Defense, then renting out the purloined PCs or using them himself to pocket tens of thousands in fees from adware vendors.

Jeanson James Ancheta, 20, of Downey, Calif., was arrested by the FBI and charged in a 17-count indictment of, among other things, conspiracy, damaging federal government computers, and illegally accessing PCs to commit fraud and money laundering, said U.S. Attorney Debra Wong Yang's office in Los Angeles in a statement.

In the 52-page indictment, Ancheta was said to have used a customized version of the " rxbot" bot worm to infect as many as 400,000 computers, rented out access to the botnet to others, and illegally installed adware on the compromised computers that generated thousands each month in affiliate fees from online advertisers and marketing firms.

Ancheta's arrest is the first in the United States of a botnet operator, although botnet creators have been pinched in the past elsewhere. A threesome in the Netherlands, for instance, was arrested a month ago for creating and using a botnet nearly four times larger than Ancheta's. Thursday, U.S. adware firm 180solutions acknowledged that the Dutchmen had tried to cash in on affiliate fees by surreptitiously installing its software on the botnet-controlled PCs.

Ancheta also had a connection, although tenuous, to 180solutions.

The indictment alleges that he used his botnet to install adware from Quebec-based, adult entertainment-oriented Gammacash and CDT, Inc., another Canadian adware vendor which ran an affiliate program called LOUDcash. In March 2005, 180solutions acquired CDT; LOUDcash is now called ZangoCash Canada.

But Sean Sundwall, 180solutions' director of marketing, denied that Ancheta's activities were directly related to the Seattle-based adware company.