Live Journal was the one place where Lynn Gilderdale felt safe uttering her deepest, most troubling thoughts. Using a ­specially-designed handheld ­computer, and ­adopting the pseudonym Jessie Oliver, it was on the internet networking forum that she shared her desire to die with her closest friends.

After suffering a severe form of ME which left her bedridden and unable to speak or feed herself for all of her adolescent and adult life, she had decided she was never going to recover, and wanted to ensure her life would end before total degeneration robbed her of all dignity.

The revelations about her decision were made to her parents, Kay and Richard, and her small group of friends in the last two years of her life. To those who were invited to share her innermost thoughts it was a painful, yet understandable, choice.

Many of them were girls and young women who suffered the same illness; some, such as Lynn, had been confined to their beds and housebound for years as a result of ME.

"She did mention to me and very few others that she had an overwhelming desire to die," said Emily Levick. "I recall the time I first read about it. I cried, and then immediately texted her, as she was so afraid that her friends would think badly of her for it, and I wanted to reassure her that I could never think badly of her.

"She had battled for so many years, and was so desperately tired. It was quite literally heart breaking to read something like that, but I did understand her reasons. I believe I would have felt exactly the same if I were in her situation."

Her mother and father were kept well informed of her decision. A Do Not Resuscitate note was placed on her ­medical notes under her own wishes and she later went a step further and directed that a "living will" should be drafted in which she stated her wish not to be resuscitated or subjected to any medical intervention if her quality of life was too poor.

"She knew it was very difficult to talk to me about that subject because no one wants to hear it coming from their ­daughter," said Richard Gilderdale, a former policeman.

"I always used to say to her I was a coward because I listened to what she said and then she would always look at me with a knowing look in her eyes and say, 'Look, it's never going to go away, dad.' Her feelings were that she had made up her own mind that she couldn't carry on."

Yet despite this clear statement of her intentions, and fresh guidelines from the director of public prosecutions to reassure relatives who help the terminally ill end their own lives, Kay Gilderdale was brought before the criminal courts this month charged with the attempted ­murder of her 31-year-old child.

After she was acquitted of attempted murder today amid applause in court, the trial judge joined campaigners, friends and lawyers to ask why was she ever prosecuted?

Kay Gilderdale was the second mother this year to face a criminal trial for the death of her child. Last week Frances ­Inglis was convicted of murder after giving her brain damaged son Tom an overdose of heroin. Lawyers say the Gilderdale case highlights the fudge over the law on assisted suicide in this country.

While the DPP's guidelines are ­supposed to reassure relatives of the terminally ill that they will not be prosecuted for assisting suicide, they do not address cases where the sick person is so ­incapacitated that helping them involves the relative taking direct action to end a life, said Saimo Chahal, the lawyer who represents Debbie Purdy, whose legal challenge led to the latest guidelines.

Lynn's friends say it would have been beyond her comprehension, having expressed her wishes so clearly and her admiration and love for her parents so fervently, to have ­foreseen that the mother who tended to her every need for the 17 years of her illness, would be prosecuted for following her wishes and helping her to die.

A criminal judge, well used to the difficult balancing act when considering any assisted suicide, questioned the necessity and wisdom of the prosecution six months before the Gilderdale trial at Lewes crown court, East Sussex

Pointing out that the accused had admitted aiding and abetting suicide, he invited the Crown Prosecution Service to drop their case of attempted murder against her.

"It strikes me," he said, "that it may not be in the interests of justice to pursue [this] when the defendant has pleaded guilty to a substantive count like that.

"[Assisted suicide] is a serious charge that appears to address exactly what happened. Wouldn't it be better to accept it now rather than let this defendant get tangled up in a messy trial for the sake of some legal mumbo-jumbo?"

For the last fortnight that legal mumbo jumbo has been played out in court. Kay Gilderdale, a dignified women has sat smartly dressed in the dock listening intently as her actions were depicted by the prosecution as an attempt to murder her daughter. She was only saved from a charge of murder because the toxicology tests had not been clear as to which dose of morphine or lethal drugs – the one Lynn administered to herself or the one her mother administered had killed her.

Behind her in the public gallery family members listened as the details of Lynn's existence were explained to the jury.

Until 14, Lynn had been a bright and sporty schoolgirl, who lived with her family in Stonegate, East Sussex. But after a BCG vaccination she was struck down by ME and within four months was unable to move from the waist down. As the illness progressed she became bedridden, lost her ability to swallow and was fed through a nasogastric tube.

She communicated through a sign language, which she developed with her parents. In later years she used her computer to communicate online with fellow sufferers, building up a network of friends.

Lynn would frequently describe her fervent love for her mother in emails and texts to friends online. In one, written during one of her many hospital visits she said to a friend: "You asked if my parents are able to visit and the answer is they actually never leave my side. One of them's ALWAYS here and mum sleeps here too.

"It's because I was treated so horrifically when I was first ill... so many mistakes have been made with my care here... mum/dad continue to do everything for me."

The dedication of her mother extended to every aspect of Lynn's life, according to friends. On her 31st birthday in September 2008, three months before her death, she told her mum how very much she would like to hear her online friends' voices, as she couldn't physically meet them.

Her mother sent emails to a number of friends to arrange the surprise and on the day Lynn watched videos prepared by some friends, and listened to voice messages from others. "It meant the world to her," said a friend.

As the years went on her communications online had become increasingly desperate until in 2006 Lynn began talking about ending her life. "I'm tired, so very, very tired," she wrote in one communication. "I can't keep hanging on to an ever-diminishing hope that I might one day be well again...

"My spirit is broken", she said, adding she would seize the opportunity to leave the world "with both hands".

Her final hours and the acts which led to Mrs Gilderdale being charged, began at about 1am on 3 December 2008. She picked up a syringe of morphine – which she used daily to cope with the pain – and injected herself . But the dose was not enough and in the early hours Lynn begged begging her mother to help end her pain. For an hour Kay Gilderdale tried to persuade her daughter that now was not the time, but her decision was made and in the end the mother opted to help her child carry out her wish.

Over the next 28 hours Kay Gilderdale neither ate nor slept as she helped Lynn die. At about 3am she handed Lynn two syringes each containing 210mg of morphine, which Lynn administered herself. When it became clear the morphine was not enough, and with Lynn now unable to administer anymore herself, Mrs Gilderdale searched the house for tablets. She crushed together anti-depressants and sleeping pills with a pestle and mortar and inserted them into Lynn's nasogastric tube.

At about 2am on 4 December ­Gilderdale gave her daughter two or three doses of morphine and later gave her three syringes of air, in an attempt to cause a fatal lung embolism. She also made a desperate ­telephone call to Exit, the assisted suicide helpline, to ask for help.

At 7.10am that day her daughter died and the exhausted mother sent her ex-husband a text saying: "Please can you come now, be careful, don't rush."

Hours later Kay Gilderdale was arrested on suspicion of murder.

From the moment her daughter died Kay Gilderdale admitted what she had done. In a conversation with the family GP, notes of which were written for the police, she took the doctor through the last 28 hours of her daughter's life.

She formalised this admission at a court hearing last July, admitting aiding and abetting suicide, which carries a 14 year maximum sentence. Despite the challenge by the trial judge the prosecution insisted it was in the public interest to charge her with attempted murder.

Simon Clements, head of the special crime division in the CPS, said: "Once the evidence had identified that this was a case of Mrs Gilderdale, on our evidence, trying to kill her daughter, we were into the territory of attempted murder.

"So clearly our policy has always been that people are not entitled to take the life of another person, however sympathetic one might be to the circumstances and the state of health of the person concerned. It is a desperately sad case but we have to apply the law as it stands unless parliament changes the law."

But Chahal said the case exposed a flaw in the law which had to be addressed.

"The law does not recognise the concept of a mercy killing attempt," she said, "which is what this case is about – a request by a daughter to a mother to assist her to die, in circumstances where the daughter … was not able to complete the act of suicide.

"There really needs to be a distinction made in law between somebody like Kay Gilderdale, who was acting out of love and compassion for her daughter and a cold blooded murderer taking a life."

Mercy laws

The Netherlands

In April 2002 the Netherlands became the first country in the world to legalise mercy killings. Under Dutch law patients experiencing unbearable suffering are allowed to request euthanasia.

Belgium

In May 2002 Belgium followed suit, partially legalising euthanasia in cases where the patient is terminally ill and makes the decision to die.

Luxembourg

In February 2008 the Luxembourg parliament voted in favour of legalising euthanasia. The Grand Duke of Luxembourg refused to sign the bill into law, and subsequently had his power of veto removed. Since April 2009 a doctor can, after consulting with a colleague, carry out euthanasia or assisted suicide in cases where the patient is terminally ill and has repeatedly asked to die.

Oregon, US

In October 1997 Oregon enacted the Death with Dignity Act which allows terminally ill Oregonians to voluntarily end their lives through the self-administration of lethal medications, prescribed by a doctor.

Holly Bentley