Belgium has been gripped by another case involving missing children. It is nearly three weeks now since two schoolgirls, aged seven and 10, disappeared in the city of Liege.
The missing girls dominate the news in Belgium
The police have used helicopters and sniffer dogs in a desperate search for them and have sifted through the city's collected rubbish.
A suspect, Abdellah Ait Oud, 39, turned himself in to police after the authorities had publicised his details, but has denied any involvement.
On Wednesday Belgian police discovered two bodies.
The disappearance of the girls brings uncomfortable memories of a horrific case in the same city, which started with two eight-year-olds going missing in 1995.
They were been abducted, chained in a dungeon, repeatedly raped, and left to starve. Two teenagers were taken the same year, and after similar treatment are thought to have been buried alive.
Two other girls were eventually rescued. The man who abducted all six, Mark Dutroux, was sentenced to life in prison.
What shocked many people was the fact that Dutroux had already been convicted in 1989 for abduction and rape of five girls and sentenced to 13 years in prison, but was released after just three years.
Should those who commit sex offences against children ever be released?
Roger Stoodley, a retired senior detective who worked on murder and child abuse cases for many years in southern England, says it is very difficult to justify releasing from prison a paedophile who has killed or seriously assaulted children.
Marc Dutroux is unlikely to ever leave prison
"Paedophiles have a mindset different from other people's, most of them think that what they are doing is quite normal and they reoffend at every given opportunity."
Most people use the word "paedophile" loosely. Their understanding of the word is based on high-profile media cases, which usually involve abductions, rape and even murder.
But experts, like Ray Wyre, who has been working as a consultant in the area of child sex abuse for over 30 years, think it is important not to use the word paedophile when talking about murderers like Dutroux.
"Mark Dutroux is a killer, an abductor, and a sadistic offender, who doesn't reflect the vast majority of adults who sexually abuse children," he says.
In the paedophile world, Mr Wyre says, "adults form a relationship with a child, they make the relationship secret, and they introduce sex into it, putting the guilt, blame and responsibility on the child, making it impossible for the child to tell anyone."
In Canada, sex offenders including those who offend against children, are automatically required to attend treatment programmes as a parole condition.
Professor Bill Marshall, an Australian working in Ontario, has 37 years of experience in treating sex offenders, many of them paedophiles.
He treats inmate sex offenders of whom - he says - only just over 3% reoffend. The treatment is a combination of psychological therapy and, when necessary, medication.
He uses the so called anti-androgens, drugs that lower testosterone levels, or the selective seratonin reuptake inhibitors, or SRIs, "which have been shown to control all manner of impulses like smoking, shoplifting and obsessive compulsive behaviours".
The killing of Sarah Payne by a known paedophile shocked the UK
But are paedophiles curable? "I wouldn't use the term curable because this is not some medical disease that you can be cured of. These people have control of their behaviour.
"They don't grab a child in the middle of a public place and assault him; they are very careful about the way they go about it. They choose to offend against children.
"Whether the guy goes in his grave still being interested in children - as long as he never does it again - I don't care what's inside his head. I care about him stopping hurting children."
Experts agree that treatment - which is expensive, complex, long, and drawn out - can help paedophiles change their behaviour.
'Why was I abused?'
But only those paedophiles who get caught are referred to experts for assessment. The vast majority - some experts say perhaps 95% of them - do not get caught.
Many child victims do want to know why they were abused. Shy Keenan, now in her early 40s, was sexually abused for years from the age of eight - by her stepfather and a number of other men.
"I've wrestled with this problem all my life - why did they do it to me? I spoke to one of these child molesters. I asked him - what is it that would stop you? What kind of treatment would help you?"
"His response was 'I like molesting children, it's great, what I hate being is a child molester, and if I could stop it tomorrow, I would'."