`Marjory Fisher is too ambitious for her own good. ... She's not prosecuting Caroline, she's persecuting her' - Michael Dowd `I think Caroline acted with depraved indifference to this baby's life' - Marjory Fisher
Today, Briton Caroline Beale goes on trial in New York, charged with killing her newborn baby. The case is likely to hinge on her mental state, which has sparked a bitter feud between the two lawyers involved.

"I didn't kill my baby. She was born dead. I could never have hurt her." Caroline Beale told me this last week, inside Rikers Island Penitentiary. The prison has now been her home for more than six months.

On 23 September, Caroline Beale was arrested at New York's JFK International Airport. Her behaviour at a security check had made police suspicious. When they searchedher, they found the corpse of her newborn baby. Within hours they had charged the 30-year-old from Chingford, Essex, with second- degree murder.

No one except Caroline Beale knew of her pregnancy. Not her parents. Not Paul Faraway, the baby's father and the man who shared her bed for 10 years, although he was with her when she was arrested.

Later today, in the New York borough of Queens, Ms Beale's murder trial is due to begin with an evidence hearing. If convicted, she would spend at least 15 years in jail. "I'm terrified I'll be forgotten," she says, picking at the drab fabric of her prison overalls and wiping away tears. "Some days I'm optimistic, other times I wake up and can't get out of bed, everything seems so bleak."

There is no doubt that Caroline Beale's baby was born alive. The autopsy report says the baby had "aerated lungs". The New York coroner, Dr Kari Reiber, says the baby would have moved and cried for several minutes. The crime scene photographs from the airport show a large, normal baby who appears to be sleeping peacefully.

Ms Beale had travelled to New York for a holiday with Mr Faraway and his two brothers, Dominic and Samuel. They were staying at a downmarket hotel in East SoHo. When she had the baby, which she calls Olivia Ann, she was alone. Her three companions were drinking at a local bar. She had returned to the hotel room to rest after complaining of stomach pains.

According to Professor Channi Kumar, of the Maudsley Hospital in London, what happened next helps to prove that Caroline Beale was not responsible for the death of her child. Professor Kumar is a leading authority on mental illness during pregnancy and one of three expert witnesses who are expected to testify in Ms Beale's defence.

He recently visited her in prison and conducted a psychiatric assessment. His conclusion is that she was suffering from "clinical delusions" that made her think her child had died in her womb several months before she gave birth.

In his report he writes, "[At the hotel] she rested, took a warm bath which eased the pain, but it returned and she took a second bath, during which the pains became extremely severe - as though her body was ripping apart. She remembers crying out for Paul and she thought she was dying." After the baby was born, "she recalls the baby not moving, or crying or breathing, it looked white".

Professor Kumar then recounts how Ms Beale placed the baby in a plastic bag, which she sealed. "After placing the baby in the bag, which is analogous to returning the dead baby to a kind of womb, she reverted to a detached state. When her partner returned, she again behaved as if nothing had happened."

Professor Kumar has no doubts about his diagnosis. "Ms Beale's actions and behaviour during this whole episode do not display the hallmarks of rational thinking and behaving," he explains. "Ms Beale has suffered and continues to suffer from a major and significant psychiatric illness. It is appropriate to treat her for mental disease rather than to charge her with a criminal act."

That defence will be presented by Michael Dowd, Ms Beale's attorney. Mr Dowd is well known in New York. He runs the Battered Women's Justice Center at the city's Pace University and is frequently quoted in the local press.

"This is Mike's comeback case," says Marjory Fisher, a 37-year-old mother of two young boys and an assistant district attorney for Queens County. She will prosecute Caroline Beale and was one of the first to interrogate her last September. "Mike is an interesting choice to defend Caroline. He's only just got his licence back after serving four years of a five- year suspension. He needs a high-profile victory. But the evidence against Caroline is very strong."

"Marjory Fisher is too ambitious for her own good," says Mike Dowd, a tall Irish-American who is just a little beefy and who smokes far too much to be fashionable in these antiseptic times. "The way Fisher's handling Caroline's case, I'll be able to paint her as the enemy of women. She's not prosecuting Caroline, she's persecuting her. When I play that card, her career will come crashing down like a crystal chandelier."

Mr Dowd has warmed his feet by the fire of New York politics for more than 15 years. In 1977, he worked on Mario Cuomo's campaign for mayor. In 1983, he defended four self-confessed members of the IRA against charges of gun-running. But in 1990 he got too close to the flames.

Mr Dowd had supplemented his legal practice with a small business called Computrace, which collected parking fines on behalf of Queens County, for a commission. In 1982, Mr Dowd agreed reluctantly to pay bribes to city officials in return for a city contract reputed to be worth $1.6m. Mr Dowd and his partner paid corrupt officials a total of $30,000 over two years but then decided they had had enough. In the resulting scandal, the Queens borough president committed suicide and Ed Koch, the New York mayor, was booted out of office.

Mr Dowd was promised immunity from prosecution. But in 1990 the courts decided he had waited too long before making his confession. He was found guilty of professional misconduct and suspended for five years. Mr Dowd avoided unemployment because his old friend Mario Cuomo had become New York's governor. Mr Cuomo found him a job in the Office to Prevent Domestic Violence.

One of Mr Dowd's last cases before his suspension is still his most famous. He won an acquittal for Ann Green, a paediatric nurse. Ms Green smothered her first child in 1980 and her second baby two years later, but the deaths were not considered suspicious until she tried to kill her third child. Mr Dowd argued that Ms Green was not responsible for her actions because she was suffering from a psychotic form of postnatal depression. The jury believed him. It was the only time a postnatal psychosis defence has been used successfully in a New York state murder trial.

"I think the Ann Green case went to Michael's head," says Marjory Fisher. "That victory has already forced the defence to make mistakes. They started by saying Caroline was suffering from postnatal psychosis, just like Ann Green. So all of Caroline's friends and relatives were primed to say how normal she was before the baby's birth. But postnatal psychosis hardly ever kicks in during the first 24 hours of a baby's life. Even Kumar's book says that.

"So now they've suddenly changed tack. Now they're saying Caroline was clinically depressed before the baby was born. But, because of their earlier tactics, they are having a tough time finding people who will say Caroline's behaviour was abnormal." Ms Fisher looks me hard in the eye: "And that includes the baby's father."

Ms Fisher is right about that, to a point. "Caroline's obviously guilty of a few things, like not telling me about the baby," Paul Faraway says from the couple's home in Leytonstone. "She didn't seem ill to us, she was just a bit withdrawn. But, looking back, there were small subtle signs that I missed. I suppose it's pretty obvious now that she was mentally ill. But I still have difficulty tracing all this back to Alison Taylor."

Alison Taylor died in June 1994 of cancer. She was engaged to Paul Faraway's brother Dominic. Ms Beale had known her for seven years and the two had become close friends in the two years before Ms Taylor's death. According to Ms Beale's psychiatrists, the painful nature of Ms Taylor's illness and death sent Ms Beale into a psychotic state that worsened during her pregnancy.

She had learnt she had accidently become pregnant two days after Ms Taylor was told she must have her ovaries removed. "I felt so guilty," Ms Beale says. "I couldn't tell anybody about the baby once I knew Alison would never be able to have children."

After Alison Taylor's death, Caroline Beale says she fell into a deep depression. In his report, Professor Kumar writes: "Her depression was characterised by persistent tearfulness, she regularly awoke around 3am and would go downstairs to cry. Once or twice she had `visions' of Alison in her room. ... After Ms Taylor died in June 1994, Ms Beale began to think that the baby inside her was also dead, it wasn't moving and her abdomen hardly grew. She now felt unable to tell Paul because he would have to cope with two deaths - first Alison's and now his baby's."

Professor Kumar says Ms Beale's belief that her baby was dead meets all the clinical criteria for a delusion. He also says it explains why she did not seek help when the baby was born.

Ms Fisher is not impressed: "Lots of people lose somebody close to them and don't kill their babies." It is then that she reaches for Ms Beale's file and pulls out a photograph of the dead child. "Look, this baby was a beautiful little girl. On the evidence so far, I think Caroline acted with depraved indifference to this baby's life. I'm prepared to be persuaded Caroline was sick, but it's also just as likely that she had some other motive for killing her baby."

Ms Fisher will probably apply for another adjournment of Ms Beale's case today. "I haven't had my experts examine Caroline yet and I need their reports in court with me," she says. "Until they've done that, Mike Dowd can ambush me. He can use his experts to argue that Caroline was mentally incompetent at the time she was arrested and so was incapable of understanding her rights."

If Mr Dowd could prove that, it would invalidate a large part of the evidence against Ms Beale. "I think Caroline was fully competent when we cautioned her," says Ms Fisher. "But with an insanity plea we need experts to say that."

What about Ms Fisher's ambition, to which Mr Dowd disparagingly refers? "Mike is so full of shit," she says. "If I won the lottery tomorrow, I'd be home with my boys in a flash. Until that happens my job is to speak for the victims. I can't do that if I make it easy for attorneys to use the insanity defence."

Whichever way it is cut, Caroline Beale herself is a victim - at least of fate. Had her baby been born 48 hours later, she would have been back in Britain. It is doubtful then that the baby would have died. If it had, Ms Beale's treatment under English law would have been very different because of the 1938 Infanticide Act, which expressly acknowledges the tragic role mental illness can sometimes play in pregnancy.

But Ms Beale must wait, for a trial or maybe bail. Today she will have been woken up at 4am to make the journey to court. "I hate court days," she says. "Because of this murder charge they shackle me, hand and foot. Then they lock the handcuffs to a belt round my waist. I can barely move and I feel as though everybody is looking at me, thinking I'm evil. ... It seems all they want to do is humiliate me."

She sits silently for a while, thinking. "All I know is, I miss Alison so much. She would have known what to do. I still don't understand what happened."