Shannon Matthews was "totally betrayed" by her mother, whose motivation for kidnapping her was purely financial, the senior investigating officer in the case said yesterday.

"The one person that Shannon should have been able to rely on more than any other person is her own mother," Detective Superintendent Andy Brennan said.

"Shannon has been totally betrayed by her own mother. Karen's interest and motivation throughout this has not been for Shannon or anybody else, it's been for her and getting her hands on £50,000."

The officer said it was still unclear what the real truth was behind the kidnapping as Matthews had told five different versions of what happened. At various times she went from playing the role of distraught, innocent mother to blaming her former partner, Craig Meehan.

She also accused Donovan of acting alone. In another version she asked him to take Shannon while she plucked up the courage to leave her partner.

"Although she has started to give away elements of the truth, even now I don't think we have got the full truth from her," the detective said.

"She has given her version of events ... I just don't think she will ever tell anybody the truth because of the seriousness of what has happened.

"She has started to tell a series of lies and she has gone round in circles and she has deserved to be found wanting. I don't think we will ever get to the bottom of precisely what the motivation was, other than the fact it was of a financial nature."

He added: "It really does beggar belief that a mother would put her own child in this position."

The court was told Shannon was given the sleeping pill temazepam and anti-travel sickness pills to make her drowsy. The drugs were administered over a number of months before her kidnapping.

The detective said Matthews would have had no idea what effect the drugs would have had on her daughter and the girl was lucky to be alive.

"If she had died I don't think we would ever have got her back. Donovan, I'm sure, would have disposed of the body and I don't think Karen would have helped us," he said.

Mr Brennan praised the role of the media in the case, saying they had played a "huge part" in keeping it in people's minds.

He added: "I think it would have been very difficult for Donovan to move her around in any way, shape or form and he would have ultimately needed to dispose of her somehow.

"Had he taken the opportunity to remove her from the Dewsbury Moor area, we probably would not (have) got her back alive."

The officer said the £3m investigation was "money well spent" because Shannon was found safe and well.

He described Donovan as a "sad, pathetic individual" who tried to give the impression to the police and the court that he was the victim.

Donovan was able to lead a normal life but when he was caught red-handed he tried to make out he was bullied and sad, he said.

He added: "He's a complete liar and he's always come across as a sad pathetic individual, but behind that there's someone who clearly knows what they are doing."

Mr Brennan said his team would look at any new evidence that came to light.

"We will look at any evidence which implicates others who may be involved in this particular case. Clearly a number of arrests were made early this year. They have been released off their police bail now. If evidence comes to light which implicates them or others of being involved, we will deal with it."

Describing when he heard the news that Shannon had been found safe and well, he said it "stopped me in my tracks" as he was expecting her to be dead.

He said one of his officers had remarked: "You can't buy moments like that."

Speaking outside court, Mr Brennan condemned the convicted pair.

"Karen Matthews is pure evil," he said. "She started deceiving those closest to her from the very moment that Shannon was kidnapped. Friends, neighbours and family were under the clear impression that Shannon was genuinely missing.

"They had no reason to believe that Shannon had been taken as part of an elaborate scam or hoax. It's difficult to understand what type of mother would subject her own daughter to such a wicked and evil crime.

"Karen Matthews is a manipulative individual who has demonstrated a remarkable ability to lie.

"Michael Donovan is an accomplished liar. Following his arrest and during this trial, he has attempted to portray himself as a weak-willed individual who only acted under duress. We have never accepted this as an accurate reflection of his involvement in Shannon's kidnapping and false imprisonment."

The detective praised all those involved in the investigation. "The residents of Dewsbury Moor and Dewsbury worked hand in hand with the West Yorkshire Police from the very first search on the first night until Shannon was recovered," he said.

"I cannot praise these residents highly enough for their support and assistance. I would like to pay tribute to the police officers and police staff who worked on this inquiry."

He said his staff had worked "relentlessly over 24 days" and on occasions more than 16 hours per day.