When Tony and Corinne Mackin reluctantly opted for a registered childminder for their baby, Joseph (six months), and his sister, Samantha (2), Helen Stacey seemed the ideal choice.
The twice-married mother lived nearby, could work flexible hours, and - just five months earlier - had been approved by Norfolk Social Services. She appeared devoted to her own baby, nine-month-old Monique, and "was very safety-conscious".
"She had all the necessary certificates, including first aid. Everything was how it should be," said Mrs Mackin (36), an auxiliary nurse and herself a former childminder who had been forced back to part-time work by financial necessity.
But all was not as it should be. For the 41-year-old was a former prostitute with four convictions for soliciting and two for shoplifting whose three older children had been taken into care or given up for adoption.
A bureaucratic loophole, caused by social services' failure to check if she had a previous married name ensured her past went undetected. The only child of Ivan and Brenda Green, Helen Stacey was brought up on an unprepossessing 1950s estate on the edge of Norwich and became a prostitute in her teens.
At 17, she met her first husband, Nick Owen, a compulsive gambler and part-time criminal 23 years her senior. They married in 1975, when she was 18. In the same year, she was convicted for soliciting and he for living off immoral earnings. Owen, with whom she had two children and whom she divorced in 1983, described the defendant as a once striking woman. "She was a blue-eyed blonde. She was always smart. She had nice clean suits, high-heeled shoes, leopardskin dresses. She always had lots of her own money to spend on such things." But she had a more secretive, and darker, side. "She was very quiet. She would not let anybody know what she was up to. She kept herself to herself," said her former husband.
Such apparent detachment - which may have been connected to the depressive illnesses which plagued her from her late teens, and which she also failed to reveal to social services - prompted a somewhat cavalier attitude to child-rearing, according to her former sister-in-law, Ms Denise Olley.
"She never harmed Joy - she was in perfect shape when Social Services took her - but she would do daft things like leave her," said Mrs Ollie. On one occasion, she left the baby in her pram outside some shops and took a bus to Norwich. When Joy was six months old, the authorities moved in - taking her into care after the couple left her in their car as Stacey went shopping and Owen popped into the bookie's.
Stacey volunteered her second child, Judy, for adoption at birth. The third child, also a girl, was placed with a private adoption agency at birth.
Sometime in the late 1980s, she met her second husband, John Stacey. The couple set up home in a tranquil, modern cul-de-sac on the edge of the market town of North Walsham, and began to bring up Monique, now 23 months old.
It was the birth of this baby, in August 1996, which prompted her to contemplate becoming a childminder. As she explained to the court, "my husband had taken a job which did not pay so much. We needed the money but I would not want to leave my daughter with anyone else. I wanted to be with her all the time so I decided to find something to do at home."
But just two months into her new profession her unsuitability emerged as her temper flared. And it was six-month-old Joseph who paid the price.
Britain's National Childminding Association jumped to the defence of the council at the centre of the Mackin murder case yesterday, saying no vetting procedure was "foolproof".