POOR little mite. How will he cope? Few people won't have had that thought when they heard that three-year-old Alex Nickell was found clinging to his mother's body after she was murdered last month on Wimbledon Common. But Alex was, perhaps, lucky. The little boy's importance as the only witness to the crime has ensured that the police have provided him with the best help available to young victims of trauma.

Dr Jean Harris Hendriks is one of three specialist psychiatrists at the Royal Free Hospital in north London. For the past month she has been seeing Alex and his father three times a week in an effort to help the child overcome his ordeal and reveal details of the murder. The Royal Free team specialises in treating post-traumatic stress disorders in children, especially where they have witnessed one parent murdering the other. Since 1986, they have seen 130 children from 50 families.

Dr Harris Hendriks will not discuss Alex's case. But the Royal Free is known to debrief children by encouraging them to relive what happened through games, story-telling and drawings in an effort to enable them to master their anger and their fears.

Without psychiatric care a child like Alex might never recover - and would also be incapable of providing any information about the murderer. 'Our job,' says another member of the Royal Free team, Tony Kaplan, 'is to provide short-term crisis intervention - first aid that helps the child and family make order out of chaos.'

Memory in a three-year-old is intensely visual, but Dr Kaplan says it would rarely take in a whole scene, concentrating instead on small details. Alex may have concentrated on the attacker's face and weapon, but might find it difficult to pick him out in black-and-white 'mugshots', unless the attacker had outstanding features, such as staring eyes or a beard.

Treating children like Alex presents particular problems for psychiatrists and the police. The trauma of witnessing a murder impedes the child's recovery from the grief of suddenly losing a parent. Younger children, says Dr Kaplan, 'feel their mother's safety is inextricably bound up with their own. An assault on her is as emotionally intense as an assault on them directly. An older child may protect himself from the pain of his emotions by fantasising about intervening in the attack or calling for help. A child of Alex's age can't do that.'

The needs of the police can, and often do, conflict with those of the child. In Alex's case, they urgently need information that only he can provide, but it may take time before he will sufficiently trust a therapist to talk about what has happened.

Recent studies by two Californian psychiatrists - Robert Pynoos and Spencer Eth - show that child murder witnesses have vivid memories of what happened, especially of the final lethal act. 'Their memories are as intense as flashbacks,' says Dr Kaplan. Some children will have looked away at the final moment; others remain transfixed by what happened and their sensory perception will be particularly acute.

Although Alex was so traumatised by the attack he couldn't speak for some time afterwards, he may remember the sight and sound of the attacker, his mother's screams and sudden silence, and the eventual wail of police sirens. Very rarely do child witnesses suffer from amnesia or disbelief about the reality of what they have seen.

The younger the child, the more severely they will feel their own helplessness as well as that of the victim. Nightmares, bedwetting, startle responses and physically clinging behaviour are all common in child witnesses, and some may regress so far that for a while they will only eat babyfood or take a bottle. Younger children, Dr Kaplan says, will be most affected by other people's response to their trauma, and will clam up if they feel the therapist is shocked or distressed.

The personality of older child witnesses, in particular, may be deeply affected by the attack. They will have watched the assailant, the victim, others at the scene and their own activity as well, and may come to identify with any of the participants. Children who identify with the assailant are often those who have been unable to stop watching while the parent was killed, and may be prone to violence in later life.

In the absence of formal records, there is no direct way of calculating how many of the 500- 600 murders that occur every year in England and Wales involve a parent killed in the presence of a child. Research undertaken in Los Angeles indicates it could be as high as 20 per cent there, and the Royal Free team suggests that the figures are only slightly lower here. Most murders take place in the home, and by far the largest group of victims are people in their mid-twenties to forties - those most likely to have young children. However, research into caring for child witnesses is very limited, and was virtually unheard of until 10 years ago.

The Royal Free's approach to treating children was pioneered in California, where much work has been done on the treatment of post-traumatic stress disorders both in adults and children.

In an initial 90-minute interview the therapist will provide a supportive and safe environment in which the child is encouraged to 'revisit' what happened. Toddlers like Alex often cannot find the right words to show their feelings, but even pre-verbal children will express their trauma through games or pictures that are often accompanied by vivid sound effects. One small child in their study carefully painted her nails red and then drew a picture of her mother covered in stab wounds.

By asking them about the drawing or story, Dr Kaplan says, the interviewer draws the child towards the event. 'We are always surprised at how quickly children get down to dealing with the trauma,' he says. Small children find free recall difficult, but their memories will be quite acute if they are prompted.

This debriefing is difficult and exhausting. The surviving parent who normally is there with the child often cannot bear to hear the attack being recounted, and so the therapist, Dr Kaplan says, usually does the debriefing alone. The parent will be told afterwards what the child has said.

Helping children cope with their experiences is harder when they are very young. Older children may have fantasies of revenge or even unbearable feelings of guilt that they survived. They will make an effort to overcome their sense of helplessness during the attack by fantasising about punishment or retaliation. This is particularly the case where the assailant has been a stranger, rather than another family member. Younger children, especially, will place great emphasis on making the victim 'better'. They may need to act out a story in which a doctor stitches up a stab wound, or draw an intact image of the victim.

While she is treating Alex Nickell, Dr Harris Hendriks will almost certainly, at some stage, discuss how he can help the police. The common assumption that it is somehow cruel to involve a small child in a murder hunt - by taking him back to the scene of the crime, as Alex's father did, or by making him attend an identity parade - is not proven. Alex may find it helpful to know that he had a role in the arrest and punishment of his mother's murderer.

(Photograph omitted)