Obsession that turns to violence: Damaged children may become dangerous if warning signs are not heeded, says foster parent Joan Clark

Looking back over the life of the child abductor and murderer Robert Black, his obsession with little girls had been obvious. As a child he sought the company and attention of little girls; he liked looking at them and touching them if he could.

A schoolmate remembers that, though he was attracted to girls, Black lashed out with his feet if one passed by. Why, asked the mother of one of his victims, wasn't Black given treatment then, when his abnormal interest was first noticed? Brought up in foster and residential care after being abandoned by his mother, he claimed to have been sexually abused by a member of staff in a children's home.

For my family, it brought a chilling reminder of an experience we had three years ago with a child we fostered. We had been foster and adoptive parents and had moved on to special fostering.

We dealt with the children at the sticky end, the ones who had suffered most. It was our job, over a period, to discover whether they had the ability to adapt to family life, whether they were adoptable, and to bring them to a level of functioning where 'ordinary' adoptive families could cope. We had therefore a recognised ability and expertise in dealing with deprived and abused children and we worked well with a range of professionals for more than 14 years.

Ian (not his real name) was nearly nine when we took him, and suffered from foetal alcohol syndrome because of his mother's alcoholism. Although this affected him to some degree both mentally and physically, he looked cute.

His main difficulty, however, was what the social workers called 'problems over gender identification'. In fact we quickly realised that Ian didn't have a problem; he was quite clear that he wanted to be a girl. The problem was the social workers', in being unable to accept this.

When my daughter left her bedroom Ian waited to sneak in, to put on her clothes and play with her dolls. If perfume was left around he drenched himself in it, and he didn't play with boys, only girls. He desperately wanted their company, but from the beginning it was obvious that he soon made them uncomfortable in a way they couldn't put a finger on.

We began to notice the absolute obsession he had with girls. He watched them playing outside with a fixed concentration that wasn't normal in a child of his age, and he even followed them in the street.

Once, alerted by an oddly disturbing giggle he had, we discovered him with a girl in the backyard, playing a game, he said, of tracing outlines. Ian was tracing the girl's outline against a wall, and when we found him his hands were between her legs.

She was clearly ill at ease and felt there was something not quite right about this game, but was probably too young to know how to object. There were also a couple of instances of him exposing himself, which he always explained away as a mistake or an accident. We kept a closer eye on him.

A pattern began to emerge, a picture of Ian that the social workers either hadn't noticed or hadn't told us about. He craved the company of girls, and because of his appearance and his seemingly unthreatening feminine demeanour, they tolerated him at first. He didn't just want to be with them, however, he had to do something to them. He grabbed one little girl by her hood and smashed her face against a wall. Though he claimed she had hit him, there had been no provocation; in fact she had ignored him, which for him was the same thing.

He followed another child along the road, screaming obscenities until she was hysterical and ran panic-stricken to her home. Unluckily for Ian, her brothers were there and they beat him up.

Then one Saturday morning he leapt on my youngest daughter as they watched television with the other children. He pinned her on the slope of the settee, got on top of her and put his hand up her nightie. All the time he giggled, that laugh we had come to recognise when he was up to no good with girls.

First he said my daughter had challenged him to a fight, then he said he had been 'giving her a tickle'; he felt absolutely no shame or remorse. The incident fitted into the general picture. He abused girls in whatever way they were most vulnerable, what he did to them depended on what kind of children they were.

We then requested the social workers to remove him and prepared a detailed, written report on his time with our family. We said he was not suitable for adoption because his difficulties were severe and deeply ingrained. In our opinion he needed long-term therapy. If not, we were convinced we would see his name again someday, for attacking and possibly killing females, young or adult. We were so concerned, that we requested that our report be given to any family asked to take him in the future.

The reaction of the social workers was entirely predictable. Part of the dogma is that every child has an inalienable right to a family, and any family is better than none. This leads to the belief that no child is a lost cause, which is as unrealistic as it is absurd. There are children who are so damaged that they are unable to form relationships or handle the intimacies of family life. Ian fitted the bill in every particular.

The social workers' only way of dealing with the situation was to defend themselves and to say that we were to blame. They decided we simply didn't like the child, and that was why we had put in such a bad report, to blacken his name. We thought we were appealing for help for him before it was too late.

Fostering is supposed to be an equal partnership between carers and social workers, but it can't be if the social workers hold all the power. After this experience, we decided never to foster again.

A psychologist who saw Ian at our request formed the opinion that he had been sexually abused at some stage, and he confirmed the child's sadistic attitude to people. What Ian needed, he said, was ongoing therapy with parents who were really therapists, and while therapy was progressing, he should not have unsupervised access to girls.

Three years later we have heard that he has been placed with another family, but I would be willing to bet anything that his new carers haven't been given access to our report.

When he leaves the care system in years to come I have no doubt that girls will continue to absorb Ian, though he may have progressed to women by then. I fear his name will crop up in police reports, and some other bereaved and haunted mother may well ask why he didn't receive treatment, and why, like Robert Black, he was allowed to roam the streets.