'One day I'm going to have to tell him what happened'

HIS first sex offence came in 1985 when, aged just 17, Neil Strachan was convicted of indecency.

In 1997, by then a football referee in Edinburgh and a youth club official, Strachan was jailed for three years for repeatedly molesting a five-year-old boy. At the time, Sheriff Andrew Bell branded the attacks "particularly disgusting and disgraceful".

Coincidentally, 1997 was the year that Britain introduced the Sex Offenders' Register, after a series of child sex crime scandals. From then on, any offender convicted or cautioned for crimes committed under the Sexual Offences Act had to be registered and monitored on a regular basis by the appropriate authorities.

Fast-forward to 2009 and the end last week of a harrowing ten-week trial in which Strachan emerged again from the shadows, along with seven other paedophiles, and was found guilty of a sickening sex attack on an 18-month-old toddler he was babysitting. He later sent a picture to his perverted mates in what came to be known during the trial as the "Hogmanay image".

Strachan may well have been registered under the act and he may well have been monitored by a network of agencies. But none of the procedures put into place more than a decade ago stopped him from offending again. Until he made a mistake in 2007 by sending his computer hard drive for repair where indecent images were spotted by an alert technician, no-one other than his co-conspirators knew he was at the centre of a worldwide web of child pornography.

Strachan's case has a familiar ring. In 2004, eight-year-old Mark Cummings was murdered by Stuart Leggate, who was also a registered sex offender.

Yet a 2006 Scottish parliamentary report into the failings in the case – led by the now SNP justice secretary Kenny MacAskill, then in opposition at Holyrood – that made 33 recommendations to tighten up the system has yet to be fully implemented. Yesterday, MacAskill suggested that there were some failings in the monitoring system without making reference to the 2006 findings.

Labour's deputy justice spokesman, Paul Martin, who has campaigned alongside Mark's mother Margaret for stricter monitoring of offenders, said: "I don't think we can be satisfied with the way the sex offenders register currently works. There is a public view that offenders are required to present themselves or are visited by police regularly, but it's not as sophisticated as that."

Scottish Conservative justice spokesman Bill Aitken said: "The Scottish Government needs to bring to the parliament a report into how the sex offenders register is operating and I will be writing to Kenny MacAskill asking for this."

And the mother of the 18-month-old boy abused by Strachan has demanded an inquiry into how the registered sex offender, a trusted family friend, was able to carry out the abuse and how they were in the dark about his previous convictions despite the fact he was supposed to be monitored.

How does the register, on which about 29,000 offenders are currently named, work? Firstly, all convicted sex offenders must register with the police within three days of their conviction or release from prison. This is monitored by the police, who should be notified by the courts and both the prisons and probation service following an offender's release. Failure to register is an offence in its own right.

Those on the register must also inform the police within three days if they change their name or address; they must also disclose if they are planning to spend more than seven days away from home. Convicted sex offenders also have to register with their local police every year. Failure to comply is also an offence.

It doesn't end there. All forces are allowed to swap information about the movements of offenders, with a national computer database set up to help make this system work. Police can also apply for orders that ban sex offenders from certain areas frequented by children.

High-risk offenders may even be subjected to further surveillance, including supervision orders and electronic tagging. Failure to comply can mean the offender is sent back to jail.

How long offenders spend on the register depends on the severity of the sentence. Those sentenced to more than 30 months are placed on the register indefinitely while for those cautioned it is two years.

The Home Office says 97 per cent of convicted sex offenders are on the register although some pursue an itinerant lifestyle to disappear below the radar. Critics say some serious offenders slip off the register because they were not sentenced to long enough in jail.

The biggest gap, however, appears to be in who else knows about an offenders' presence in their midst. Although head teachers, doctors, youth leaders, sports club managers and others, including landlords, are notified on a confidential basis, there is no general disclosure on civil liberties grounds.

Imprisoned for 36 months in 1997, Strachan fell into the most serious sex offenders' category. Released early in 1999, he was made the subject of a year-long supervision order. During that time, monitoring was the responsibility of a criminal justice social work team including Lothian and Borders Police, NHS Lothian and Edinburgh City Council. At the end of the order, his monitoring was then taken over by the police. Periodic reviews were undertaken by the joint police, council and health service team.

To everyone involved in his case, 41-year-old Strachan was a reformed character, with a job at the Crown Decorator Centre in Newhaven and living quietly with his younger partner, 23-year-old Colin Slaven.

Yet the reality was very different. Strachan befriended a couple with two young sons and was taken into their trust so much that they allowed him to babysit while they went out to celebrate Hogmanay. Not only did he abuse their 18-month-old boy, he distributed an image of himself committing the act to his circle of paedophile friends around Scotland. Last week, Slaven was convicted of possessing indecent images with a view to distributing them.

The authorities clearly believe no blame is attached to them. As Lothian and Borders police said after the convictions last week, an internal review of Strachan's case had shown he had been "appropriately monitored". Detective Superintendent Allan Jones, who brought Strachan and his co-conspirators to justice, could only add: "When you encounter duplicitous, determined characters such as Strachan, it is very difficult to ensure these instances aren't going to happen. He did present himself as an individual who was rehabilitated but, clearly, he wasn't."

But the mother of Strachan's 18-month-old victim says any claim the man was being properly supervised was "rubbish".

Speaking last week she said: "If they had been monitoring him properly, they would have known he could have come into contact with my boy. They would have contacted me to say 'Strachan's a sex offender – be careful what you do with your children.' I think there should be an investigation."

She added she fears the effect the abuse will have on her son, now four. "I dread the day I have to tell him what happened."

Paul Martin is also among those who believe monitoring of serious sex offenders is too lax. "Leggate was on the register when he murdered Mark but there was no monitoring – he just had to tell the police his address," he said.

He is also concerned about delays in implementing recommendations agreed by the Scottish Parliament's Justice 2 committee in 2006. They included fuller disclosure of offenders' whereabouts and tighter monitoring of internet activities.

"A total of 33 recommendations were made following Mark's murder, which Kenny MacAskill signed up to at the time, and they have not all been implemented," he said.

"We need to make sex offenders tell housing agencies and private landlords of their convictions and they (offenders] need to be socially profiled so police know which clubs they are a member of and which internet sites they are visiting.

"We also need a proactive approach from police so they have more effective reporting mechanisms, and we need to be able to differentiate between sex offenders who have committed serious and lesser crimes so we know where to put the resources."

Despite the passage of three years, four recommendations remain outstanding. A Scottish Government spokesman said: "We have been working with law enforcement agencies to implement recommendations submitted to the previous administration by the justice sub-committee. Nearly all have now been delivered. However, we have given an undertaking to provide a detailed report to the parliament and would not preempt that at this stage."

Timeline of a sickening case that shocked the nation

1985 Strachan convicted of a child sex offence at the age of just 17.

1997 Strachan jailed for three years and registered as a sex offender for molesting a boy of five over two years while an official at a youth football club.

2004 Strachan and James Rennie meet online for the first time.

December 2005 Strachan photographs himself sexually abusing an 18-month-old boy, later sharing the image with Rennie.

August 2007 Two months after being diagnosed as HIV positive, Strachan takes his computer to a repair shop in Reading, where an IT engineer discovers a single image of a naked boy. Police uncover a further 7,223 encrypted pictures and videos, and begin sifting through chat logs.

November 2007 Officers search the Edinburgh address shared by Strachan and his partner, Colin Slaven. They find computer equipment that Slaven admits contains indecent images of children. Strachan is arrested.

December 2007-April 2008 Police raid the home addresses of the other six accused – none of whom have criminal records – seizing various pieces of computer kit. All are arrested. Later analysis reveals a total of 125,000 images of child pornography.

February 2009 Trial of the eight begins after they plead not guilty to charges of possessing and making indecent images of children.

May 2009 High Court jury finds the eight accused guilty of possessing and making indecent images. Five are also found guilty of conspiring to abuse an infant who had already been molested by Rennie. They will be sentenced at a later date.

Who's who

JAMES RENNIE, 38, from Edinburgh, chief executive of LGBT (Lesbian Gay Bisexual Transgender) Youth Scotland. The self-confessed "sex addict" was a trained teacher and youth worker. He held a senior administrative role in which he no longer had contact with teenagers at the advice centre. He had a boyfriend but trawled the internet for gay sex dates, picked up rent boys and advertised a porn collection on toilet walls. The court heard Rennie had links with paedophiles in America and Europe.

JOHN MILLIGAN, 40, from Govan, Glasgow, civil servant. Milligan had no life outside his Job Centre office and every night spent hours in front of his home PC. He had hardcore child pornography among the 125,000 images found by police experts who examined the gang's computers. The court heard of his fantasies about missing Madeleine McCann.

COLIN SLAVEN, 23, from Edinburgh, IT worker. Lived with Neil Strachan in the Dalry area, after beginning on-off affair with him as a teenager. After turning up to court so drunk he could hardly stand, he was found guilty of contempt by Lord Bannatyne. His bail was revoked and he was locked up for the rest of the trial.

CRAIG BOATH, 24, from Dundee, insurance clerk. An insurance claims worker who wanted to be a police officer. Investigators found a shocking video of a six-year-old girl, and thousands of photographs.

NEIL STRACHAN, 41, from Edinburgh, service engineer with a paint firm. The convicted sex offender was jailed for three years in 1997 at Edinburgh Sheriff Court for abusing a boy aged between five and seven during his time as secretary of an Edinburgh-based boys' football club. Started affair with teenager Colin Slaven on his release.

JOHN MURPHY, 44, from Govanhill, Glasgow, sauna receptionist. The trained teacher worked as a receptionist at a gay sauna and DJ in a gay bar as well as working part-time as a journalist. Police investigating the case found 117 paedophile images when they raided his flat.

NEIL CAMPBELL, 46, from Bearsden, Glasgow, cake shop manager. Well-respected church-goer who helped with a children's after-school club. Despite being married, he had a gay partner. Police discovered he used his wife's e-mail identity online to persuade boys to perform sex acts.

ROSS WEBBER, 27, from North Berwick, bank teller. The counter supervisor in Gullane, East Lothian had stored 188 indecent images between August 2006 and January 2008.