If McCanns were Portuguese 'they would already be in jail' says 'wrongly convicted' killer

Convicted killer Joao Cipriano, 35, said if the couple were not foreigners in Portugal they would have been tortured into confessing and then jailed over their daughter Madeleine's disappearance.

He and his sister Leonor, 36, claim they were forced into confessing to a crime they did not commit – the murder of Leonor's daughter Joana, who went missing in 2004 - and have warned that the McCanns could be framed by the police.

They are serving 16-year prison sentences for the killing but insist they are innocent, and are taking their case to the European Court of Human Rights.

In a letter to Portugal's Attorney General, Cipriano said he believed his niece was abducted from her home and then sold.

He wrote: "If the McCanns were Portuguese, they would have been put behind bars, tortured, charged and condemned."

His sister has told of her fears that Mrs McCann could be framed for Madeleine's disappearance, as she insists happened to her after her own daughter went missing from Figueira, near Portimao.

Joana was eight when she vanished, less than 40 miles from Praia da Luz, and police have never found any trace of what happened to her.

Her mother was made an arguido and said she was thrown down a set of stairs and made to kneel on broken glass until she confessed. Police claim she threw herself down a staircase.

Three officers are facing disciplinary hearings over claims they beat her and the former head of the Madeleine inquiry, Goncalo Amaral, is facing charges that he helped to cover up the alleged torture.

He was in Portimao police station when Mr and Mrs McCann, both 39, were taken for questioning, and when detectives allegedly told Mrs McCann she would receive a lighter jail sentence if she confessed.

There is no suggestion that either of the McCanns was physically abused by detectives.

But their lawyers have studied the Cipriano case and their private detective agency, Metodo 3, has investigated whether Joana and Madeleine could both have been targeted by a paedophile network.

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Metodo 3 is also investigating the disappearance of a Spanish five-year-old, Mari Luz Cortes, last weekend from the city of Huelva, only 120 miles from Praia da Luz.

Mrs McCann sent a personal note to the girl's parents and yesterday Mari's mother Irene Cortes said it had given her strength.

The 30-year-old, also a mother-of-three, said: "From my heart I hope I can now give her hope and strength.

"Mrs McCann use all your strength to carry on, don't give up. I believe Madeleine will be found."

Mrs Cortes said she felt a shared bond of suffering with the McCanns, and had never believed they were involved in the eight-month-old case.

She said: "With all the speculation that Mrs McCann could be guilty of killing her child, I said that's all lies, I didn't believe it.

"A daughter is very special, for a mother to do anything like that is unthinkable, impossible."

The Cortes family has vowed to campaign for their daughter's safe return like the McCanns have, and even hope to start an appeal fund like the £1.2million Find Madeleine fund.

In a touching message to her daughter, Mrs Cortes said: "Don't cry my baby, try to be strong. Mummy is waiting for you. Please don't cry, I love you."

Mari has not been seen since she left her family's apartment in Huelva to go and buy a bag of crisps.