By Mark Williams-thomas
Last updated at 12:36 AM on 10th March 2010

I was deluged by strangers asking stomach-churning questions about my sexual experience. I was pressured to meet men with whom I’d never before communicated.

So I wasn’t surprised that a vulnerable teenager, Ashleigh Hall, was groomed on Facebook before being brutally raped and killed.

Paedophiles’ playground: Child sex offenders actively search for young girls on social networking sites who will fall prey to their false charms (posed by model)

Anyone who knows what an adventure playground social networking sites offer paedophiles would only be surprised that such tragedies don’t occur more often.

For the internet is full of people with sexually deviant desires – the level of danger goes way beyond even the most worried parent’s imagination.

Child sex offenders existed before the internet, but with the inviting, anonymous environment such sites provide, they have greater access and opportunity, which they exploit all too readily.

For these depraved men are not just lurking online hoping youngsters will find them; they are actively searching for young girls who will fall prey to their false charms, as I discovered when I set out to investigate this dangerous environment.

I am vastly experienced in the field – I was a police detective specialising in major crime and worked on some of the biggest murder and paedophile investigations in the country, before gaining a masters in criminology and setting up a child protection consultancy.

I knew the enormity of the problem, but I wanted to make public how easy it is for paedophiles to approach youngsters online.