Calling her over, Cuevas told the girl she had bubble gum stuck in her hair and she was going to fix it. Quickly, she pulled out five strands, placed them in a napkin and put them in a plastic bag. She had picked up the trick from cop shows and knew that to prove this feeling in her gut she would have to get a DNA sample.

Tests proved that her instinct was right, the little girl known as Aaliyah was in fact Delimar Vera. And just as the 31-year-old had always suspected, the baby who was supposed to have died in a fire aged just 10 days, had been alive all this time.

In December 1997, a woman posing as the child's mother is alleged to have stolen her from her bedroom in her family home in the poor Philadelphia suburb of Frankford, and started a fire to cover her tracks. Carolyn Correa, 42 - a cousin by marriage of Delimar's father, Pedro Vera, and a regular visitor to the family home - is believed to have taken the baby a few miles across the state line to Willingboro, New Jersey, and pretended to her family that the child was her own. She called her Aaliyah after the singer, sent her to private school and groomed her to be an actress and beauty-pageant princess.

Correa has since been charged with kidnapping, arson, assault, concealing the whereabouts of a child and interfering with the custody of a child. Her lawyer says that he is considering an insanity defence.

Cuevas has said that she never believed firemen when they told her that her daughter had perished in the fire. They said the baby's body had been so consumed by the flames that they could find no remains. But her mother remained suspicious. Why had the baby's crib been empty when she ran through smoke to get the child out? Why was the bedroom window open when it was a freezing cold night outside? Why were there no remains at all?

The hysterical mother screamed at the firemen that she thought her baby had been stolen, but she was told "maybe it was my nerves". A death certificate was never issued because a body was never found. Cuevas says she wanted the matter investigated by police at the time, but on learning what lawyers would cost she realised that she could not afford to pursue the matter.

Despite all that, Cuevas had always held on to the feeling that her daughter had not died. On January 24, at the children's birthday party, she told her friend that she was sure the little girl was her child, Delimar. "When I see her, I saw that she was my daughter. I want to hug her. I want to run with her," she told the American media.

Determined to prove her case, Cuevas turned to a local politician for help. State representative Angel Cruz listened to Cuevas's story for an hour and a half, but found it hard to take in. He was sceptical but "something inside" made him think that this bizarre tale could have some foundation in truth.

Cruz called the police and Correa was given a DNA test that showed that Aaliyah Hernandez was indeed Delimar. When Correa arrived to give a second DNA sample, the child was taken away from her. Correa was taken into custody on $1m bail, leaving many questions. Questions such as how friends and relatives of Correa believed her story for so many years? If she did steal the baby and set the house on fire, who helped her, since the police seem to be in no doubt that she had an accomplice? Why did she call her former husband three days before the fire to say she had given birth to a little girl?

When she was first separated from Correa, Delimar screamed and wailed. According to the assistant district attorney, Leslie Gomez, Correa said, "Goodbye, this is the last time you're going to see Mommy." Delimar was then temporarily placed with a foster family.

When she first formally met her real mother, lawyers reported that the child hid under a table and popped up shouting, "Surprise". When asked by Cuevas, "Do you know who I am?" the little girl replied, "You are my mother".

Cruz told ABC television: "She [Cuevas] got a hug and kiss; her daughter sat in her lap. The moment she expected six years ago, she got it."

American social services recommended that the reunification of the family be part of a slow process, but the state governor decided the child should be given back to her real family "as soon as possible". Experts say this may well be a mistake.

Late last Monday night, Delimar arrived at her new family home. Wearing a blue hooded top and pink trousers, she was ushered in the back door to a welcoming party that included her three brothers, aged four, 10 and 11. "I'm at my real home," the child told reporters. Asked how she felt, she replied with a giggle: "Happy."

But will it be that easy? Child welfare experts and psychologists predict not. Her world has been turned upside down. Suddenly she has no access to the woman whom she has always thought of as her mother, the siblings she thought were her siblings, or the grandparents she is said to have cherished. Her brutal separation from that previous life may lead to insecurities and confusion. Not only that, but the girl who knows herself as Aaliyah Hernandez has been brought up speaking English; her real mother is a Spanish-speaker with only a slight grasp of English. Then there is the shock of being told that the mother she loved has been arrested and accused of kidnapping her from her crib when she was a baby.

Jillian Lindon, a clinical psychologist specialising in working with children, says a girl of six would be unlikely to understand what has happened to her.

"She has been separated in a really precipitate way from her parents and her family. I would expect she will suffer considerable grief. What this little girl is going to have to do is take on board not only a new mother but also what has happened," she says.

"It will be quite traumatic and could have severe consequences for her and her ability to form attachments. How can she trust anybody after this? How can she reattach to this mum? How does she know somebody is not going to come along and remove her?"

Professor David Messer of London Southbank University's department of child psychology says: "One very important thing is that, generally, if the child can keep in contact with the previous person who has been looking after them, then it's not so sudden a change, full of trauma and difficulties. To be separated from that person - as in this case - is going to be quite difficult."

But it isn't all gloom. He says: "Children can be amazingly resilient. One has got to be optimistic. Gradually the child can come to understand that the other person wasn't fully balanced and, even though the child had affection for that person, she will come to realise that what she did was wrong."

To make things even more complicated, the newly reunited family could soon be embroiled in a new set of legal battles as Cuevas's estranged husband, Pedro Vera, has said he intends to seek shared custody; at the moment he has visiting rights. Cuevas has since produced her daughter's birth certificate with the father listed as "unknown".

But Cuevas is confident they can overcome these hurdles. She has said: "I believe in my heart that she will accept me." For now the little girl will still be called Aaliyah. "Little by little, I will call her Delimar."

The little girl with the dimples may already be used to the limelight; she has her own agent, has appeared in TV ads and had bit parts in movies. Her mother is even considering book and movie deals - fielding offers from 25 different producers - and has retained three attorneys and what has been described as a "showbiz lawyer". But a time of quiet is what they may really need. After posing at the door of her new family home, Delimar said to reporters: "Don't come no more. Please don't."