The police case against the main suspect in Madeleine McCann’s disappearance appeared to be on the verge of collapse last night.
An ex-boyfriend of Christian B, 45, gave a damning statement against the convicted child sex fanatic.
But sources close to the German investigation say their key witness is “shaking” and threatening to stop his help.
Police are hoping to catch Christian B because of Madeleine, who disappeared in 2007 when she was three years old.
A damning statement from Helge B – an old pal of Christian B – has become a cornerstone of the German-run police case.
But sources close to the investigation warn that he may soon back down and refuse to back up his claims in court.
A German source told The Sun: “It is said that Helge B is about to withdraw his statement.
“He was paid a huge sum for repeating his statement in a German newspaper and now he is pulling the plug.
“It just shows you what kind of people you’re dealing with – and how credible they are as witnesses.”
Helge B’s move could be the final blow in the halting attempt to bring Christian B to justice over the alleged kidnapping and murder of three-year-old Madeleine in Portugal in 2007.
It will be another setback for her parents Gerry and Kate, both 55, from Rothley, Leics.
German Helge B, 48, was a criminal buddy of drifter Christian B when the pair were living in the Algarve when Madeleine disappeared from her holiday apartment in Praia da Luz.
He told police he was dismayed by Christian B’s alleged dark confession when the two met at a music festival in Spain shortly after the tot’s disappearance.
While the couple discussed the case over a beer, Christian B is said to have coolly admitted: “She didn’t scream.”
The convicted rapist and child abuser clearly indicated that he had kidnapped Madeleine, Helge B told the police.
McCann investigating prosecutor Hans Christian Wolters said he knew nothing about Helge B’s alleged change of heart – but stressed that his testimony would still carry weight.
He said: “Everyone who has said something must be judged by it.” Witnesses are obliged to tell the truth – they have to testify. You can’t just choose something like that.”
Helge B’s threats to quit came when it was revealed that Christian B had written begging letters to friends asking them to support him if he went to trial.
He faces new charges of rape and child molestation that are unrelated to the McCann case.
In a letter, the sex offender complained that the prosecutor’s office portrayed him as a “monster.”
An ex-boyfriend said: “I know two people in the Algarve who received the news. It really scared her.”
Christian B is currently in prison in Germany for the 2005 rape of a 72-year-old American woman in Praia da Luz.
Investigators say they have “concrete evidence” that Madeleine is dead, but have not yet provided any other material that could lead to charges.
Christian B.’s lawyer, Friedrich Fulscher, declined to comment yesterday evening.