GERMAN cops were warned months ago they could wreck the probe into Madeleine McCann’s disappearance by relying on a witness dubbed “the Bulls****er”, sources claim.
Police were depending on a damning statement made by an ex-pal of prime suspect Christian B, 45, to crack the case.
The Sun exclusively revealed today how sources close to the German probe say their key witness Helge B is “wobbling” and threatening to stop helping.
His statement had become the cornerstone of the German-led police case – but insiders claim he could soon back out and refuse to support his claims in court.
Now sources have told The Sun how German officers were told long ago about Helge B’s “flakiness” – and that their reputation is now “shot to bits”.
One source close to the investigation even revealed some Portuguese officers even nicknamed the star witness “Helge Bulls****er”.
He said: “Helge B is someone the Portuguese officers have known about for a long, long time. But he was discounted as a credible witness ages ago.
“He was always seen as a Walter Mitty character who would talk “BS” all the time hence the nickname.
“They warned the Germans he was a bit of a fantasist and that he was ‘flakey’ and how he’d say what you wanted to hear. But, for some reason the German detectives latched on to him.
“They’ve pinned pretty much their entire case on his evidence, despite being warned he wasn’t to be trusted. Now, with him looking to back out, their credibility has been totally shot to bits.”
The insider said German cops likely held onto Helge B’s account as they have no other leads.
The source added: “The biggest problem in all of this is that the German cops have nowhere else to go right now.
“There are no new leads and no evidence they have. Without this guy’s curtains.”
Helge B’s move could be the final blow in the stalling bid to bring Christian B to court for the suspected abduction and murder of three-year-old Madeleine in Portugal in 2007.
A German source told The Sun: “Word is that Helge B is about to withdraw his evidence.
“He was paid a huge sum to repeat his statement in a German newspaper and now he’s pulling the plug.
“It just goes to show you what type of people you are dealing with — and their credibility as witnesses.”
If Helge B pulls out, it will be another setback for her parents Gerry and Kate, both 55, of Rothley, Leics.
German Helge B, 48, was a criminal pal of drifter Christian B when they lived in the Algarve around the time of Madeleine’s disappearance from her holiday apartment in Praia da Luz.
He told cops he was chilled by Christian B’s alleged dark confession when the pair met at a music festival in Spain a short time after the tot vanished.
As the pair discussed the case over beers, Christian B was said to have coolly confided: “She didn’t scream.”
The convicted rapist and child sex attacker clearly implied he had taken Madeleine, Helge B told cops.
McCann probe prosecutor Hans Christian Wolters said he was unaware of Helge B’s suspected change of heart — but insisted his statement would still carry weight.
He said: “Anyone who has said something must be measured by it. Witnesses are subject to the duty of truth — they have to testify. You can’t just choose something like that.”
Christian B is currently in jail in Germany for the 2005 rape of a 72-year-old American woman in Praia da Luz.
Detectives claim to have “concrete evidence” that Madeleine is dead but have yet to produce further material which could lead to a charge.
Christian B’s lawyer, Friedrich Fulscher declined to comment.