Prosecutors tasked with investigating the prime suspect in the Madeleine McCann case have hit a major stumbling block after it was revealed the main witness is facing a possible perjury charge.

Convicted rapist and paedophile, Christian Brueckner, was named as the prime suspect for the abduction and murder of 3-year-old Madeleine from a Portuguese holiday complex in 2007.

The current case against Brueckner was built around key witness Helge Büsching’s testimony.

Büsching is said to have claimed that Brückner confessed to him about his involvement in Madeleine’s disappearance.

The year after Madeleine disappeared, he claims to have had a conversation with Brueckner in which he said it was “odd that she didn’t scream” when they discussed her disappearance.

Prosecutors believe Christian Brueckner is responsible for Madeleine McCann's disappearance and death. Photo / Handout

When asked in 2020 what he thought of Brueckner, Busching said: “One word. Guilty.”

At the time he also told investigators he stole videotapes from Brueckner which he alleges showed a range of chilling and disturbing crimes.

The witnesses’ claim about the videotapes was used in an unrelated case to jail Brueckner for seven years for raping and sexually assaulting two women.

It was believed these tapes were hidden in a caravan.

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In a startling twist, Büsching changed his statement in January 2023, claiming the tapes were not left in a caravan, but instead were left on a rural property he once lived in alongside another witness.

However, they have never been found.

Now Bruckner’s lawyer Friedrich Fülscher has hit out at Büsching’s credibility, citing the inconsistencies in his statements.

The witness could now face a possible perjury charge with Bruckner’s lawyer alleging he gave an “unsworn false testimony”.

“As a witness, this man is completely unbelievable,” Fülscher said.

The Daily Mail claims sources close to the investigation claimed that when contradictions in the case were pointed out to Büsching, he then refused to co-operate further after speaking with his lawyer.

Brueckner’s lawyer is now seeking a suspension of his rape sentence and a retrial.

During his trial, the court heard he planned the sex attack having broken into the victim’s house with a rope to tie her up. She was blindfolded and gagged before being raped and robbed.

He is also being probed over a series of sex attacks and rape between the early 2000s and 2017 in Algarve.

Brueckner denies any involvement in the Madeleine McCann case.

Now German prosecutor Hans-Christian Wolters, the man tasked with finding out who abducted and killed Madeleine, will have to weigh up whether Büsching’s evidence is still consistent and strong enough to be used against Brueckner.

It has been reported the probe into Brueckner’s involvement in the Madeleine case is on the brink of collapse.

Büsching’s apparent unwillingness to further help authorities could see any prosecution of Brueckner slip away.