Vincent Barron, 50, a senior probation service manager, was seconded to the Home Office ViSOR project because of his expert knowledge of offenders.

He helped set up a national computer database containing the details and pictures of more than 60,000 of the most dangerous criminals, including 25,000 registered sex offenders.

Yesterday at Durham Crown Court he was jailed for 33 months after admitting 21 charges of distributing indecent images and one charge of possessing 3,800 indecent images.

The charges relate to an investigation in Scotland into a paedophile using the Internet name "BigGordy76".

Fife Police found links with someone using the online pseudonym "doggingcpl2004" – subsequently unmasked as Barron.

Police raided Barron's home in Kirk Rise, Frosterley, County Durham, and found a computer containing indecent images. Last year he was convicted in Scotland for distributing child pornography.

Durham Crown Court was told how police experts found chat room transcripts between Barron and another man of "vile fantasies" depicting rape and murder.

They also discovered the massive haul of child pornography, including 800 of level four and five images, the most serious.

Robin Patton, defending, said Barron had lost his high-flying career, his good name and had shamed his family. "In December 2005 his voyeuristic tendencies were ended forever and he has fallen from grace spectacularly with no foreseeable prospect of being employed by anybody to utilise his skills," the barrister told the court.

"He has already fallen about as far as anybody could fall. He has brought shame to his family. He is isolated and shunned by neighbours and he has very little prospect of gaining employment at a level he was used to.

"He was drinking very substantial amounts of alcohol and it was a very unhealthy combination of a bottle of whisky or whatever he was drinking, and the Internet in the early hours of the morning."

Jailing the former assistant chief officer of Northumbria Probation Service, Judge Richard Lowden said Barron had wrecked a "fine career of public service".

Judge Lowden described the transcripts of chat room conversations as "vile fantasises" and said the offences were so serious only prison could be justified.

Barron was also placed on the Sex Offenders Register for life and banned from working with children indefinitely.

Barron was employed by Northumbria Probation Service for a number of years before being seconded to the National Offender Management Service's ViSOR project for five years.

When Barron was arrested in December 2005 he was suspended by the Probation Service and following his conviction in Scotland he was sacked.

ViSOR had been unveiled in August 2005 after the Bichard inquiry into Soham double child killer Ian Huntley called for a national register of offenders which could be shared by all police forces.

The computer system holds information on individuals convicted of sex offences, or jailed for more than 12 months for violence, but also, more controversially, unconvicted individuals who are still assessed as a risk.

The computer provides a national database for registering, risk assessing and managing sex offenders, violent offenders and others who may cause serious harm to the public.