How could a loving father kill his own child?

Lisa had no worries about leaving her partner Steve with their son: he had always been good at soothing him. But the baby died that night of multiple injuries. He is just one of 40 children murdered by their fathers in the past decade

Lisa Gearing sits on the sofa with her son Jake, who's almost one, sleeping beside her in his buggy. On top of the TV there are several colour photographs of baby Steven. Lisa gestures towards them: "When I got pregnant with him my partner Steve and I were dead chuffed. We'd been trying for a child for a long time."

Lisa Gearing sits on the sofa with her son Jake, who's almost one, sleeping beside her in his buggy. On top of the TV there are several colour photographs of baby Steven. Lisa gestures towards them: "When I got pregnant with him my partner Steve and I were dead chuffed. We'd been trying for a child for a long time."

She was 17, Steve Cunningham was 19, and it seemed like a return to the "brilliant" early days of their relationship. They had separated only a few months before, a split caused partly by disappointment at not being able to have a child and partly because Steve had been drinking heavily. But they got back together and decided to try again and, almost immediately, Lisa found she was expecting. "Steve changed his life. He more or less stopped drinking," she said. "He fed Steven, changed his nappies and cared for him a lot when I went to the shops or out with my Mam."

But, within two months of baby Steven's birth, Lisa fell pregnant again. "This time it was quite different. When I told Steve, there was no reaction. That was like a slap in the face. He didn't want to talk about it much after that. He wasn't working and may have worried about how we'd manage. But why didn't he say?"

She wonders about this, just as she wonders why he didn't tell her that he had things on his mind and didn't want to look after the baby on that night last May when Lisa was going down to the bingo hall. "I settled Steven, who was a very easy baby. He did wake sometimes and cry, but Steve had always been good at soothing him."

Soon after 9pm, there was a phone call at the bingo hall from Steve's father saying the baby had breathing problems. When Lisa phoned Steve he was hysterical. "He kept saying 'the baby's not breathing... I've bruised him trying to resuscitate him'. Even then he was making up his story. Then he just shouted 'the baby's dead!'."

They were both taken in for questioning. Lisa was released after a couple of days but Steve was kept in. He was initially charged with manslaughter after he admitted shaking baby Steven because he was crying. An autopsy found 47 bruises on the child's body, two fractured femurs, a liver so badly ruptured it was torn loose, and severe brain damage. Rather than "shaken", police believed the baby had been violently battered. After hearing about the child's horrendous injuries, the jury found Steven guilty of murder by an 11-to-one majority.

Lisa gave birth to Jake in November. While Steve was on remand they exchanged letters until Lisa asked him not to write to her any more. The trial began in January. She went to court every day, hoping to hear something that would help her understand what happened that awful night.

She feels nothing but anger and hate towards Steve. "I'd like to see him hanged," she says. She knows that one day she will have to tell Jake - who looks "the spit" of his father - exactly what happened to his older brother. She looks at me with enormous eyes in a face framed by hair cut to half an inch - it was a mane of curls once, but she chopped it off after the murder verdict.

She asks: "How could he kill his own child?" How indeed. It is the question asked with incredulous horror each time we hear of a father murdering his own child. And we have heard it chillingly often of late.

Last month, there was the case of Peter Stafford, 37, who stabbed his three young children and his wife to death before hanging himself. Weeks later, David Price gassed himself in a car with his two young children on the seat beside him.

Over the past decade some 40 children in Britain have died at the hands of a father. Last year, Steven Carter and Peter Madin set fire to cars with their children inside, then killed themselves. Simon Smith smothered his three babies soon after each was born because they would not stop crying. And Scot Kenneth McKay intended to kill his six-year-old son and four-year-old daughter when he took them hostage at their Glasgow home and slashed their throats with a six-inch knife. His son spotted the front-door key on the floor and pushed it underneath with his foot so police could get in. Had he not, they would certainly be dead. McKay then slit his own throat in front of them.

But why do these men, who have often lived with their children and cared for them lovingly, as Steve Cunningham had done, suddenly turn and kill them?

Adam Jukes, a psychotherapist who works with violent men, has written two books: Why Men Hate Women (Free Association Books) and Men Who Batter Women (Routledge). He sees these killings as "the ultimate act of revenge". They most often occur when the relationship with the mother has broken down and she has custody of the children.

"These men are full of fury at being rejected and losing their children. They dwell on their hurt and rage and often demonise the woman to a point that is completely out of touch with reality - they may convince themselves she is a danger to the children. And the one power they know they have is to inflict lifelong suffering on the mother by taking the children and leaving her alive."

This may explain the impulse, but what happens to a person that they can take a knife and stab their young to death, deliberately drive them to a beauty spot and set fire to them, pick them up and slam them against a wall? To understand we have to grasp the power of the psychotic state, says Ged Bailes, consultant forensic psychologist at the Norvic Clinic, a secure psychiatric unit in East Anglia. These men, he explains, frequently go into a psychotic state where they lose touch with reality and normal empathetic feelings. They can be flooded with overwhelming feelings, hallucinations, compulsive drives and an utterly negative view of the world. In such a state, they can convince themselves that taking the children is what must be done.

Bailes believes revenge can be a motivation, but also suggests other scenarios: "A man with a lot of personal worries, who is deeply depressed, can go into psychosis and have delusions which convince him that the children are in danger, their minds controlled, possessed by demons and that it would be kinder to end it all. Or he may want to take the children with him to a 'better place'." Then there is the man whose own inadequacies and frustrations flood over him and he takes his rage out on the child.

This could be what happened with baby Steve, suggests Jukes. Lisa's mother described how, after a few drinks, Steve would often break down and describe how he had been savagely beaten by his drunken father from babyhood onwards. "When his own son cried and he couldn't soothe him it's quite possible he was overwhelmed with the murderous rage he experienced towards himself from his own father."

Men are not, of course, the only ones who murder their children - in the past five years there have been four cases of mothers killing their babies. But Julie Bindel, Assistant Director of the Research Centre on Violence, Abuse and Gender Relations at Leeds University, says these are almost always a result of a mother's despair and depression at not being able to cope with the children in her care. It is not an act of rage and revenge.

She is convinced that if we looked deeper into these paternal murders we would almost always find a history of domestic violence. This often begins during pregnancy, she says: "Even before the children arrive they are problematic, a threat, getting in the way of the man possessing the woman completely, and getting all her attention."

We might also do well to look at the degree of distress that men experience when they lose their children, in the view of Jim Parton at Families Need Fathers: "If a man is violent he may forfeit the right to contact with his children, but I see mothers punishing fathers out of anger after a relationship breakdown by making contact very difficult when there has been absolutely no domestic violence. These men do become despairing and very angry." That was found, too, by the authors of the academic study Absent Fathers (Routledge) who state: "A major grievance was the difficulties fathers had seeing their children."

Mike Nash, a former policeman turned counsellor, points to the culture of blame that overtakes such cases. "Ultimately there can be no excuses made for these killings and we should be clear that those men who remain alive and in prison must take responsibility for what they have done and show remorse before they are ever released."

Lisa Gearing picks up Jake who has awoken. "I know Steve is not going to spend life in prison, that he'll be out and starting a new life. I don't like that. But it would help to know that he feels the pain of what he has done as I do. Every hour, every day."