Ben KendallAn 'extremely dangerous' criminal convicted of murdering a Norwich sex offender also killed a 16-year-old boy and raped and attempted to strangle a third victim, police revealed.Ben Kendall

An 'extremely dangerous' criminal convicted of murdering a Norwich sex offender also killed a 16-year-old boy and raped and attempted to strangle a third victim, police revealed.

Royston Jackson, 43, of Pettus Road, Norwich, was told he will never again know freedom after being ordered to serve a whole life sentence.

He killed 73-year-old sex offender Gordon Boon after the pair met at the John Boag probation hostel in Norwich. Jackson was living in the hostel after being released from a 16-year sentence for murdering a 16-year-old in Essex. Boon had served five years after admitting sexually assaulting three young girls.

Yesterday Jackson was found guilty of murdering Mr Boon, 73, of Helgate Court, Norwich, following almost 12 hours of jury deliberations at Norwich Crown Court.

Mr Boon's was strangled and dumped in Rabbit Lane, near Great Witchingham, in October 2008.

After the hearing retired Det Chief Insp Steve Strong, who lead the inquiry, expressed his relief at the verdict saying Jackson was an 'extremely dangerous' individual who could have gone on to kill again.

Following the investigation forensic evidence had linked Jackson to a third serious crime. He said: 'When he was entered on to the DNA database by Norfolk police we found irrefutable evidence that he was responsible for the rape and strangulation in another part of the country.

'The woman in that case did not die and it was not possible to bring a prosecution - but it highlights just how important this prosecution was in terms of protecting the public'

Probation officials said they were confident they had done everything possible to protect the public from Jackson. He had been closely monitored and there was no sign that he would breach the strict terms of his licence.

Martin Graham, chief officer of Norfolk Probation Area, said: 'We fully recognise the difficulties faced by those involved with the victim. We understand that this is a difficult time for them.

'The job of the Probation Service is to manage risk. While we have an excellent track record of success, risk cannot be totally eliminated and ultimately an offender is responsible for his or her actions.

'We have conducted a thorough review of this case and we are satisfied that Mr Jackson was being managed appropriately according to the stage of his licence and the assessment of his risk.

'However we are never complacent and the public rightly expect us to do our job properly. That is why we place a great deal of importance on good risk practice and ensuring our processes are robust.'

In court, Mr Justice Underhill told Jackson 'life will mean life' as he sentenced him. He added: 'This was a shocking murder and you have already committed one murder; you are clearly a very dangerous man.'

Mr Strong added: 'This was a very difficult inquiry for lots of reasons, the first one being the guilty man was quite clever when it came to covering his tracks - although clearly not clever enough.

'Another difficulty was the offending history of the victim which meant few members of the public felt sympathy towards him. We only received two phone calls from potential witnesses throughout the entire inquiry.'

t Do you have a crime story for the Evening News? Contact crime correspondent Ben Kendall on 01603 772423 or email ben.kendall@archant.co.uk

Gordon Boon's daughter last night revealed how she still loved her 'Jekyll and Hyde' father - despite suffering years of abuse at his hands.

Katie Utting said she had mourned his death in the way any daughter would. Waiving her right to anonymity as the victim of a sex offence, Mrs Utting, 43, from Weeting, near Thetford, said the killer had robbed her of the opportunity to seek answers from the man who abused her from the age of eight.

The crimes came to light in 2001 when Mrs Utting, more than 20 years after she was abused, became concerned that her father may be grooming another victim.

She said: 'It started when I was about eight and went on until I was 16. It began gradually but I now realise he was grooming me and over the years the abuse got more and more serious.

'He used to wait until my mum went out to bingo and then creep into my room. I knew it was wrong but I felt powerless to stop him.'

Mr Boon did not abuse any of his other four children. Over the years he and his wife fostered more than 100 other children and, despite one allegation to the police, there has never been any evidence that they were abused.

But Mrs Utting said: 'When I realised he might be abusing somebody else I knew I had to face up to it and report it to the police. I couldn't let him do that to another girl.'

Despite her ordeal Mrs Utting visited her father in prison throughout his sentence. She said she would never forgive him but had learnt to love him once more.

'Part of me hates him for what he did. I can't forget that and it will never go away,' she added. 'People might find this difficult to understand but he was still my father and after a while realised I still loved him. When the police told me he had been murdered I cried.'

She said her father had never apologised to her or explained why he singled her out for abuse. 'I kept hoping he would say sorry but he never did,' she added. to the family.

'All I ever wanted in this case was for him to be found guilty and to know he would never be let out again,' she added.