A 20-year-old Californian pleaded guilty last week to causing damage to computers in Seattle's Northwest Hospital when his bot software compromised systems in the healthcare facility.

Christopher Maxwell of Vacaville, Calif., signed a plea agreement last week accepting blame for damaging a protected computer and involving himself in a three-person conspiracy for the same crime, according to a statement released by the U.S. Attorney's Office for the Western District of Washington. Maxwell admitted in the plea agreement that he and two unnamed co-conspirators caused damage to Seattle's Northwest Hospital as well as computers at military facilities in Germany and the U.S.

The group used the bot net created by the malicious software to install adware on the computers and earn more than $100,000 in affiliate advertising income, prosecutors stated. In searching for more computers to infect, the bot software used by the group caused trouble amongst some systems at Northwest Hospital: doors to the operating room failed to open, pagers did not work, and computers in the intensive care unit were disrupted, the statement said. The hospital used backup systems to continue to treat and care for patients.

The bot software also infected more than 400 systems at the Department of Defense's Fifth Signal Command in Mannheim, Germany, and the Directorate of Information Management in Fort Carson, Colo., causing more than $138,000 in damage.

Prosecutors and consumer advocates have focused increasingly on the problem of criminals known as bot herders, or bot masters. In January, another 20-year-old California man plead guilty to compromising PCs to create a bot network. Meanwhile, consumer advocates have attacked adware companies for giving bot herders an incentive by not checking rigorously enough that installations of adware are truly wanted by a system's user. Some bot herders have gone on the defensive, using peer-to-peer technology to make their tracks harder to follow.

Maxwell will be sentenced in August. Causing damage to a protected computer can result in up to a 10-year prison sentence and a $250,000 fine, while the conspiracy charge carries up to a 5-year prison sentence as well as a $250,000 fine. In his plea, Maxwell agreed to pay $252,000 in restitution to Northwest Hospital and the Department of Defense, according to the prosecutor's statement.