San Francisco mayor Gavin Newsom has intervened personally in the case of the FiberWAN network which had been taken over by an administrator.

Network administrator Terry Childs had locked all other staff out of the system, which carries nearly two thirds of the city's administrative data.

Childs has now handed over the passwords after a personal visit by Newsom to his jail cell.

Nathan Ballard, the mayor's spokesman, told The San Francisco Chronicle that the mayor "figured it was worth a shot because, although Childs is not a boy scout, he's not Al Capone either".

Most of the network is now back under control by administrators although a few problems remain. Childs is still in prison after his bail for four counts of tampering with computer networks was set at $5m.

Initially it was assumed that Childs was simply an administrator gone rogue but a more complex picture is now emerging that raises serious questions about the viability of the prosecution case.

Childs stands accused of locking out other administrators from the FiberWAN network, but it seems that in fact he has always been the sole rights manager and management knew about and endorsed this situation.

Childs built the network from scratch and maintained it personally. Allegations that he built in unauthorised systems that allowed him access from outside the office also appear over-hyped.

It has since emerged that most administrators have some kind of remote access so that problems can be fixed out of office hours.

Childs's lawyer, Erin Crane, has said that her client was protecting the network from damage by other administrators and that the prosecution is trying to paint her client as the villain of the piece.

"This is an affront to the city of San Francisco and a miscarriage of justice," she said, adding that administrators disliked Childs and "when they couldn't get rid of him" decided to portray him as a "rogue employee" to force him from his post.

"Mr Childs had good reason to be protective of the password," the lawyer said. "His co-workers and supervisors had in the past maliciously damaged the system themselves, hindered his ability to maintain it and shown complete indifference to maintaining it themselves."

Crane is now trying to get the exceptionally high bail demands reduced so that Childs can be released from prison.

"Mr Childs intends to not only disprove those charges, but expose the utter mismanagement, negligence and corruption at [the Technology Department] which, if left unchecked, will in fact place the city of San Francisco in danger," she said.