After everything she has been through in the past 16 months, Louise Woodward probably thought nothing could surprise her. She went to America a plump and entirely unremarkable Cheshire schoolgirl to work as an au pair. She was charged with murdering eight-month-old Matthew Eappen, though she professed to adore him.

She was convicted when every expert and armchair analyst assumed she would be acquitted. Then she was freed, thanks not to some remarkable piece of new evidence, but to the instincts of an eccentric judge - Hiller Zobel - who ignored the arguments presented to his court, devised his own theory of what happened on February 4th last year, and released her on 279 days served for involuntary manslaughter.

Amazing. Woodward thought she had seen it all, but she hadn't. Last week there was another twist, which has caused just as much tumult, and could have enormous repercussions.

Woodward's lawyer and confidante, Elaine Whitfield-Sharp, appeared to have betrayed her - allegedly telling a police officer that she now believes Woodward is guilty, then describing the 20year-old as a "lying monster". This from a woman who, until very recently, was Woodward's staunchest defender.

She was the first lawyer to befriend Woodward, she visited her regularly in jail, pieced together her elaborate defence, and once the trial was over, allowed Woodward to live with her. If WhitfieldSharp's loyalty cannot be overstated, neither can the impact of her sacking from the legal team, an inevitable severance which was announced on Monday.

So what has been going on in Boston, and why are the Woodwards, her remaining lawyers and her supporters in Elton, now more anxious than ever about the future? Whitfield-Sharp's dismissal could not have come at a more sensitive time, but in a sense, Woodward and her parents, Gary and Sue, have only themselves to blame. The betrayal, if any, appears to have come from them.

The Woodward family have played a canny game since Woodward was freed, insisting in public that they have no intention of making money out of the case, while conducting secret negotiations with publishers and newspapers about selling her story. It was a high-risk strategy, and it has blown up in their faces. At the very least, the revelations are an embarrassment to the family at the most delicate stage of the legal process. At worst, it could seriously undermine Woodward's case if a retrial is ordered.

Woodward is still in the United States because Massachusetts Supreme Judicial Court has not ruled on the appeals which were presented by the prosecution and the defence teams in March. The seven justices of the SJC have a complicated task on their hands. Rather than dealing with the appeals separately, they decided they could juggle both at the same time.

The prosecution believes Judge Zobel acted beyond his powers by reducing Woodward's conviction from second-degree murder to manslaughter, and then cutting her sentence from a minimum of 15 years in jail to the time she had spent behind bars on remand.

The defence case, owing much to the efforts of Whitfield-Sharp, argues that the jury should never have convicted Woodward in the first place because the weight of medical evidence in her favour was so compelling. They want an acquittal, or at worst, Judge Zobel's decision to be upheld so Woodward can reclaim her passport and fly home to the UK.

The pessimistic view is that if the SJC wanted to find in favour of Woodward, it would have done so by now. If the justices believed Judge Zobel had acted within his powers - under the labyrinthine law of Massachusetts he has enormous latitude for discretion - they could have dismissed the prosecution case straight away. Clearly, the matter has needed further consideration than that, and the longer the justices deliberate, the edgier Woodward's team becomes.

The tension was already rising before the bespectacled Whitfield-Sharp began, as one commentator put it, to "self-destruct". The process began when she was arrested for drink-driving nearly two weeks ago. The trooper who detained her, Randy Cipoletta, had no doubts that Whitfield-Sharp was under the influence; she had apparently careered across three lanes of traffic, and then crashed into guard rails as she drove home to Marblehead, an elegant Boston suburb. When stopped she could not recite the alphabet past the letter N, or walk in a straight line.

Police Sergeant Cipoletta was also sure he had heard Whitfield-Sharp correctly when she said her errant behaviour had been caused by her belief that Woodward had killed Matthew Eappen. "I know she is guilty and I can't handle it," she told him. Whitfield-Sharp accused the officer of lying - claiming he had propositioned her for sex - but any credibility she had disappeared days later when the British Mirror published extracts from a conversation the lawyer had had with a "friend".

In fact, the friend was a freelance journalist who had the good sense to record the conversation. The freelancer was not the first Whitfield-Sharp had spoken to about her fears - she had also confided in a TV correspondent - so it was only a matter of time before her views became public. Andrew Lines, the US editor of the Mirror, could hardly believe his ears when he heard it, and quickly secured the tape before any of the other tabloids had a chance. Whitfield-Sharp laid bare what she felt about Woodward and how she believed the Woodwards had duped her.

Far from intending not to make money out of the case, Whitfield-Sharp had discovered that the family were preparing to sign newspaper and book deals for six-figure sums. The lawyer regarded this as monstrous. At a press conference shortly after she was released, Woodward had said she had "no intention of exploiting the tragedy," and WhitfieldSharp had repeated this to the media time and again. In fact, a lot had been going on behind her back, but it was only in the past few weeks that she began to uncover the extent of the wheeler-dealing.

IT BEGAN in the early days of the trial last October, when British tabloid newspapers began to scent a sensational story. Like the other lawyers on the team - Andrew Good, Harvey Silverglate and Barry Scheck - Whitfield-Sharp knew the papers would be prepared to pay significant sums for the story, but she was not aware how close the family had come to a deal.

Letters and contracts were being passed to the family by intermediaries - principally, two men who were working for the ITV documentary, The Big Story, which had covered the case from the start. It was cloak and dagger stuff in the finest traditions of Fleet Street, with reporters sneaking into the darkened corridors of the court building in Cambridge for discreet talks as the trial came to its climax.

There was never any doubt among the "pack" that Woodward wanted to sell her story. When her mother was asked what criteria Woodward would use for deciding which paper she would go with, she replied off the cuff: "If I know Louise, she'll go with the money."

Believing she would be freed, Woodward agreed in principle to sign up to a tabloid if the jury found her not guilty. The paper had promised to fly the family home first class, and had hired a suite at Boston's luxurious Harborside Hyatt hotel for a champagne celebration to mark her release. The Dom Perignon began to go flat at 9.30 p.m. on October 30th, when the jury found her guilty.

Nevertheless, the situation was not entirely lost. Before Judge Zobel set their daughter free 10 days later, Mr and Mrs Woodward talked exclusively to the Daily Mail for a reported £40,000. It was the relationship with the Mail which Whitfield-Sharp particularly objected to. Several weeks after Woodward was released, pictures of her at a Christmas party were published in the paper, which she believed could have come only from a member of the family.

The Woodwards denied any involvement, but Whitfield-Sharp was suspicious, and accused them of selling the photos. This was completely against what they had agreed, and she believed it was immoral. Her anger turned to disgust when she found out that Woodward had been visited by newspaper executives from the UK in the spring, and that she and her mother had engineered a meeting with publishers.

On that occasion, they had tried to fob her off by saying they were going to meet Silverglate. "While they were out supposedly with him, he telephoned me," Whitfield-Sharp was recorded saying. "I asked if he was having dinner with Louise and Sue and he said `no'. Some hours later Sue and Louise came back. I asked if they had enjoyed their dinner with Harvey and they said `yes'. "

At the beginning of April, and with their relationship deteriorating beyond repair, Woodward moved out of Whitfield-Sharp's house to stay with an expatriate friend, Tim Hunt. "I think Elaine started to have her misgivings about Louise when she realised an awful lot was going on behind her back," said a source familiar with the case. "I think the turmoil she has been in is a direct result of months of worrying."

The secret negotiations and skulduggery which led to Whitfield-Sharp's dismissal will mean nothing if Woodward is either acquitted, or allowed to return home with the conviction against her name. The whole matter will be forgotten.

But if the SJC rules against her and she is either jailed or told to stand trial again, then the events of the last fortnight could be crucial. She has lost a pivotal member of her legal team, and also a friend. Her dismissal, and the circumstances surrounding it, are a huge fillip to the prosecutors.

There is an added problem, which is deliciously ironic. Whitfield-Sharp is now being pursued by newspapers in the same way Woodward was last year. Potentially, she has a terrific story to sell - the definitive inside track on Woodward.