A former San Francisco network engineer was convicted of felony computer tampering Tuesday after a trial in which prosecutors portrayed him as bent on protecting his "kingdom" - the city system he created - by refusing to surrender passwords to his bosses.

Terry Childs, 45, of Pittsburg, was found guilty of a felony charge of denying computer access. The Superior Court jury also concluded that his crime cost the city more than $200,000, making him eligible for a maximum state prison sentence of five years.

However, Judge Teri Jackson is expected to impose a sentence under which Childs would serve a few additional months at most, after she gives him credit for the nearly two years he has spent in county jail since being arrested in July 2008. Sentencing is set for June 14.

Prosecutors argued that Childs had decided to wall off his supervisors from the city network he had built when he learned he could be laid off from the Department of Telecommunications and Information Services, where he had worked for 10 years. Childs also was angry that his bosses were questioning his security clearance after learning that he had previously been convicted of robbery, prosecutors said.

Newsom testifies

The four-month trial featured the testimony of Mayor Gavin Newsom, who finally obtained the login and passwords to the computer system in a jailhouse interview with Childs, more than a week after the network engineer left the department.

Newsom testified that the city had been "in peril" because officials were blocked from access to police records, payroll data and other information.

The jury deliberated for several days before a lone holdout against conviction was removed from the panel, for reasons that were not disclosed. After an alternate was put in that juror's place, the panel started over and reached a decision in a matter of hours.

Jurors interviewed after the verdict said the city had been partly responsible for letting the situation with Childs get out of control.

"We had a lot of sympathy for him," said juror Jason Chilton, who is a network engineer. "He was put in a position he should not have been put in.

"Management did everything they possibly could wrong," Chilton said. "There was ineffective management, ineffective communication. I think that if they put the city on trial, they would be guilty, too."

'Wanted to be needed'

However, he said, the panel agreed that Childs had acted illegally.

"He wanted to cement his position," Chilton said. "He wanted to be needed by the city, no matter what the cost."

Prosecutor Conrad del Rosario told jurors that when the prospect of layoffs arose in spring 2008, Childs told a co-worker, "They can't screw with me. I've got the keys to the kingdom."

When Childs' bosses asked him that July how to get into the computer system he had built, Childs first stalled, then provided bogus passwords, del Rosario said.

Childs was suspended, the prosecutor said. "At this point, the city of San Francisco (did) not have control of its system," del Rosario said.

Only when jailed, prosecutors say, did Childs finally give the information to Newsom on July 21, 2008.

No danger

Childs' attorney, Richard Shikman, said the city computer network had never been at risk.

He portrayed Childs as a hardworking, dedicated professional who sacrificed his personal life to build a system that he guarded from security intrusions.

Shikman acknowledged that Childs may have been "paranoid" about protecting the system and undiplomatic with his bosses, but nothing worse.

Childs initially refused to hand over the passwords because his bosses were asking him to do so over an unsecure phone line, Shikman said.

"All they had to do was ask him (for the passwords) in a secure and professional way, consistent with policy and standards," Shikman told the jury.

"I'm disappointed at the verdict - he's very decent man," the defense attorney said after the verdict was announced. "He doesn't deserve this."