THE key witness in the Madeleine McCann case today confessed it was the "biggest failure" of his life not to have reported Christian Brueckner earlier.
Helge Büsching, 52, called prime suspect Brueckner, 47, "really dangerous" as he told a court he was convinced that his former drifter pal snatched the British tot.
Büsching committed crimes with the convicted rapist in Portugal in the early 2000s before coming forward in 2020 to claim Brueckner had taken Madeleine.
He was rushed into court today from a safe house flanked by six masked-gunman to give evidence against the paedophile suspect accused of snatching the youngster in 2007.
He told a trial he took videos from Brueckner’s lair showing the lowlife raping an elderly woman of 80 and a girl as young as 13.
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But Büsching failed to report the horrific clips, found in 2005, to cops - meaning Brueckner was a free man in 2007 when he could have allegedly snatched and killed Madeleine.
Büsching told Braunschweig Regional Court, in Germany: “I don’t know why I didn’t take the videos straight to police.
“I regret this to the day. It was the biggest failure of my life.”
He added: “I was afraid of getting my into in legal trouble if I went and told the authorities because of the other things I had been involved. So I kept my mouth shut for a while.”
Büsching admitted to being so appalled by the clips when he met pals days later he told them to avoid Brueckner - warning: “If this guy turns up, he is really dangerous.”
The key witness also told how he took the videos because he was "curious" after finding them at Brueckner’s house, near Praia da Luz, Portugal, while he was looking for diesel.
One despicable clip showed a blindfolded elderly woman being hit and raped by Brueckner.
Büsching was also expected to tell the court today how Brueckner bragged “no, she didn’t scream” when they discussed Madeleine in 2008.
The alleged conversation took place just a year after the toddler, then aged 3, vanished from a holiday apartment in the Algarve resort town of Praia da Luz.
Büsching said that Brueckner then “….suddenly gave me a look as he had realised he had revealed that he was involved in the youngster's disappearance.
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“And then next day, without saying a word, he had upped and left.”
Büsching has a conviction for human trafficking, and was arrested in Greece in 2017 after attempting to smuggle migrants between Greece and Italy.
He said that when he first tried to alert German authorities to Brueckner's actions, he sought advice from a police officer and lawyer who both told him to drop it as he could end up implicating himself.
He also claimed he had phoned the Met Police to inform them about Brueckner’s confession in 2008, but no one called him back.
He said he tried again in 2017, after hearing about the tenth anniversary of Madeleine’s abduction.
This time, he said, he was interviewed by British police.
He was then summoned two years later to testify in a German trial where Brueckner was convicted of raping a 72-year-old American tourist, Dianne Menkes, in Portugal.
He was sentenced to seven years for the 2005 rape.
In 2020, Büsching was tracked by UK media to Corsica, where he had been working at a recycling plant and was living in a hotel.
He said he was only prepared to give one word “guilty” when asked about Brueckner and the likelihood of him being involved in the Madeleine case.
Büsching claims Brueckner’s lawyer, Friedrich Fulscher, used a string of dirty tactics via a researcher to con his way onto someone else’s Facebook account in order to track him.
Brueckner is facing a string of vile rape, sexual abuse of children and indecent exposure allegations at Braunschweig Regional Court in Germany - which he denies.
Last week, German authorities revealed that a van once driven by Brueckner was being probed thanks to The Sun.
They will examine the white Mercedes Sprinter motor that we revealed was parked at paedo Christian Brueckner’s lair after Madeleine vanished in 2007.
Germany’s federal police, the BKA, want to examine the motor amid hopes it could still contain DNA or crucial clues.
The Sun revealed the existence of the van in February.
A BKA source said: “We are on to this now and appreciate the tip," adding they were speaking to the garage where the van is being stored.
The van bombshell also followed claims that Brueckner boasted about kidnapping and sexually assaulting another girl months earlier.
Prison cellmate Michael Tatschl, 49, will tell the court this week that Brueckner had held a 13-year-old girl hostage for four days after she ran away from a youth camp.
Tatschl, an Austrian, lived with him at a farmhouse in Praia da Luz - the same Algarve resort where Madeleine disappeared - and spent eight months in jail with him in Portugal for stealing diesel from lorries.
Both were released in December 2006 — just five months before Madeleine vanished.
The trail, which began in February, is expected to last for up to four months.
