The charges that were thrown out relate to allegations that Childs quietly placed three modems on a San Francisco city network to have backdoor access to the city network. In dismissing the charges, Judge Kevin McCarthy ruled on Friday that there was insufficient evidence to show that Childs had placed the modems on the network with malicious intent.

But the judge left standing a fourth charge, that Childs refused to hand over passwords he had used to lock up the city network for days. If Childs is convicted on that count, he faces up to five years in prison. A hearing is scheduled for today to determine a date for the trial.

A spokeswoman for the San Francisco District Attorney's office today said that prosecutors in the case will appeal Judge McCarthy's ruling. In December 2008, Superior Court Judge Paul Alvarado had held that Childs would need to stand trial on all four of the counts he had been charged with, the spokeswoman said. But, in response to motions filed by Childs' attorney, three of those counts were vacated last Friday, the District Attorney's spokeswoman said.

"We disagree with Judge McCarthy's ruling. We believe that Judge Alvarado's ruling should stand," the spokeswoman said.

Childs, a network administrator working for San Francisco's IT Department of Telecommunications and Information Services (DTIS), was arrested in July 2008 for allegedly locking up access to the city's FiberWAN network by resetting administrative passwords to its switches and routers.