David Stocker's death from salt poisoning was sudden and unexpected.
The nine-year-old had spent seven months suffering from a mystery illness that baffled doctors at both his local hospital in Hornchurch, Essex, as well as the world famous Great Ormond Street Hospital in London.
Petrina Stocker denied poisoning her nine year-old son
But his death followed a series of unusual events which made doctors and nurses increasingly suspicious that his mother, Petrina, was deliberately tampering with David's samples and medical equipment in an attempt to fabricate symptoms that were not really there.
Some of David's urine samples seemed to have had blood clots added on top of them.
The vomit samples his mother showed to staff also appeared odd - sometimes looking like blackcurrant juice or smelling minty.
And on two occasions his intravenous drip appeared to have been adjusted and a white powdery substance added.
When nurses asked Petrina if they could watch David pass urine she refused, saying he was too embarrassed.
When nurses suggested moving David closer to their nursing station she again refused, saying it would make him upset.
Petrina Stocker's final attempt to deceive the doctors at Great Ormond Street Hospital proved to be a disastrous miscalculation, the court was told.
In August 2001 she allegedly went into the communal kitchen area and scooped teaspoons of table salt into the bottles containing her son's milk feed.
The prosecution claim she had no intention to kill David, saying that in all likelihood it was another ruse to keep the doctors guessing about his symptoms. Within a few days he was dead.
But how could a mother have turned on her own child - especially when he was suffering from an illness that had seen him turn from a healthy, happy child who adored karate to an anorexic, lethargic patient?
History of deception
What the jury did not know was that Petrina had experienced previous episodes of pretending to be ill.
As a teenager in 1979 she had a series of unexplained blackouts and by October 1981 had appeared to lose consciousness 20 times. The blackouts suddenly stopped that year.
In 1983 she developed a rash on her face, chest and arms which she told friends was leukaemia. She later admitted she had poured cleaning fluid over herself to get attention from her family after having her wisdom teeth removed.
By 1987 her employer noted Petrina was taking a lot of time off with unusual ailments.
When she was asked to supply a urine sample she added granulated sugar to it in an attempt to show she had diabetes.
The prosecution alleged that over many years Petrina Stocker had fabricated symptoms in herself and then in David as well.
This sort of behaviour made some staff at Great Ormond Street Hospital believe she might be showing signs of Munchausen's syndrome by proxy.
Hospital security change
An attempt was also made to transfer David into a psychiatric ward as parents of children were not admitted there.
Petrina Stocker fought the decision, saying it would make David depressed.
In hindsight it appears unfortunate - given the hospital's concerns - that David was not moved to a safer place or closer constraints put on his mother.
Although the staff had watched Stocker - in the words of the defence lawyer - "like spotlights from a watchtower" that had not been enough to prevent David's death.
Great Ormond Street Hospital said staff have introduced new security measures in the kitchen areas of the hospital wards.
Parents are no longer allowed to help prepare feeds and the feed bottles themselves are now kept in locked fridges.