A mother and father who murdered their daughter because she would not embrace their Pakistani culture were given away by a single nod.

A body language expert has analysed footage of Iftikhar and Farzana Ahmed lying to the public about 17-year-old Shafilea's 2003 disappearance, claiming they were being racially victimised, for a documentary.

It shows footage of an interview given by the parents, during which Iftikhar is asked if he had any involvement with his daughter's disappearance, to which he replies: 'Never. I couldn't even dream of it.'

A body language expert has analysed footage of Iftikhar (left) and Farzana Ahmed (right) lying to the public about 17-year-old Shafilea's 2003 disappearance

It shows footage of an interview given by the parents, during which Iftikhar is asked if he had any involvement with his daughter's disappearance, to which he replies: 'Never. I couldn't even dream of it'

However, according to expert Cliff Lansley - who shares his findings on Investigation Discovery's Faking It: Tears Of A Crime - he gives a self-incriminating nod as he gives his response.

Mr Lansley explained that the fact that his head moved in an up-and-down motion at the moment when he was pressed on his involvement in the murder, at almost the exact time he expresses his verbal denial, is a significant indication of guilt.

'He has got his eyes closed, his volume has dropped and we see the head nod yes. Slightly diagonal, but this is up and down,' he told the Mirror.

Shafilea was suffocated with a plastic bag for failing to conform to Pakistani culture

The body language expert also believes that by adding 'I couldn't even dream of it' to his original answer of 'never' he is attempting to further qualify his story, fearing his lies may be detected.

Nine years after Shafilea disappeared, the truth finally came out in court - her father had stuffed a plastic bag in Shafilea's mouth, holding it there until she stopped breathing.

It was almost six months until her body was found in the River Kent in Cumbria, some 70 miles from the family home in Warrington, Cheshire.

Iftikhar and Farzana were convicted following evidence given by Shafilea's sister after she was arrested for setting up a robbery on her own parents.

She told officers they had murdered her for failing to accept an arranged marriage, and told her siblings to keep quiet if they wanted to avoid a similar fate.

Her parents' protestations of innocence came after they arrested along with five distant family members in the immediate aftermath of the tragedy.

They were released without charge, but following Alesha's testimony they were both jailed for life.

A judge ordered both Iftikhar, then aged 52, and his 49-year-old wife to serve a minimum of 25 years in prison.

How nodding can give the game away In almost every culture in the world, nodding the head means 'yes' and shaking it from side to side means 'no', but the speed and frequency with which a nod is performed can carry different meanings. A slow nod often means someone is listening, while a fast nod means the listener is saying that they have heard enough and wish to talk. However it is wise to raise suspicions when someone shakes their head but actual says something positive, or nodding the head as they say something negative - as it could be a way of determining that they are lying. And it appears that is what gave the game away for Iftikhar Ahmed, as determined by expert Cliff Lansley. Ahmed's head moved in an up-and-down motion at the moment when he was pressed on his involvement in the murder, at almost the exact time he expresses his verbal denial. To body language professionals, this contradiction is a clear sign that he was lying and an indication of his guilt. Advertisement

Shafilea's efforts to escape her parents' iron grip were thwarted by what criminologist Dr Aisha Gill called a 'catastrophic' communication breakdown during the trial, as social workers took her reluctance to make allegations of abuse at face value.

During the interviews shown in the documentary, the parents brazenly claimed they were being victimised because they were Muslim.

Iftikhar looks directly into the camera when he says: 'They say "You're a Muslim family, Pakistani culture, this is the way you people are."

'That is the attitude they come up with, suggesting "you Muslim people do these things" - that we would kill our daughter.'

And when pressed on the issue of an arranged marriage, they also strenuously denied any involvement.

Iftikhar also confronted the camera in a separate interview after they were cleared after their initial release, celebrating his 'innocence'

It was almost six months until her body was found in the River Kent in Cumbria, some 70 miles from the family home in Warrington, Cheshire

Her father adds: 'No, because the daughter does not want to be married yet. She was still under education, she wanted to make something of herself.

'Until such time she doesn't want anything to do with a marriage, which is fine.'

Iftikhar also confronted the camera in a separate interview after they were cleared after their initial release, celebrating his 'innocence'.

He said: 'When the police are implying those things on you without any evidence, there's nothing we can do about it. We just have to bear it until the truth comes out.

'They should have let us off months ago. We should never have been on bail in the first place. It's just proven the point that we've been telling the truth from day one.'

But in her extraordinary testimony, Alesha described how her parents suffocated Shafilea with a carrier bag forced into her mouth and then hands over her face to close her airways so she could not breathe.

Led away: Iftikhar (aboe) and Farzana Ahmed (top) were two traditionalist disciplinarians who had very fixed ideas about how their children, particularly their daughters, should behave

A judge ordered both Iftikhar, then aged 52, and his 49-year-old wife to serve a minimum of 25 years in prison

Alesha then saw their mother in the kitchen 'sorting through a pile of blankets and sheets' and holding a roll of black bin bags and two rolls of tape.

She looked out the window and saw her father with a large object wrapped in bin bags with brown tape around it.

Shafilea had been a keen student at her school in Warrington, Cheshire, and enjoyed trips to shopping centres and wearing Western clothes

Shortly afterwards, she saw her father leaving in a car with Shafilea's body inside.

Shafilea had only just started college to study for her A-levels after hospital treatment for deliberately swallowing bleach while staying with her grandparents in rural Pakistan.

On the night of the murder Shafilea had been picked up by her mother from her evening call centre job.

She had been dressed in Western clothing in defiance of her parents' desire for her to wear traditional dress.

The following day, Alesha allegedly told friends her father had killed Shafilea and chopped up her body, although she afterwards denied saying it.

However her parents did not report her missing, and the alarm was only raised a week later by an ex-teacher worried about rumours of what had happened.

By contrast, when Shafilea ran away before the trip to Pakistan, they had repeatedly called her mobile and contacted her friends in a bid to find her

Faking It: Tears of a Crime airs Fridays, 10pm on Investigation Discovery.