German prosecutors are confident they can charge Madeleine McCann prime suspect Christian Brueckner over her disappearance.
The convicted paedophile, 43, is serving a 21-month sentence on an unrelated drugs matter at a prison in Kiel and will be transferred to Wolfenbuttel in January to start a seven-year sentence for raping an OAP woman in Praia da Luz in 2005.
He was identified as the new lead suspect in June after German police released a trove of new evidence including details of his cars and phone numbers, urging people to come forward with new tip-offs.
German prosecutors now say they believe they have 'concrete evidence' Madeleine is dead, and are set to charge Brueckner with three other sex crimes in Praia da Luz in Portugal, where the three-year-old vanished in 2007.
Hans Christian Wolters, who is leading the German probe into Madeleine's disappearance, said he is 'confident' with the investigation.
A source close to the probe told The Sun: 'Things are moving along in the case and there have been several promising leads and tips, especially from British holidaymakers who were in Praia da Luz at the time of Madeleine's disappearance.
German prosecutors are confident they can charge Madeleine McCann prime suspect Christian Brueckner, a convicted paedophile and rapist, over her disappearance
Christian Brueckner is the prime suspect in the disappearance of Madeleine McCann in 2007
'We are hopeful of a breakthrough. At the moment we do not have enough to charge him with Madeleine's disappearance but the evidence in the other cases is very strong.'
Brueckner was previously remanded at the prison in Kiel ahead of last year's trial for raping the elderly American woman. She was attacked just two years before Madeleine disappeared from the same Algarve resort.
Earlier this month, a court in Karslruhe rejected Brueckner's appeal against the 2005 rape conviction and confirmed his seven-year sentence.
The move will make it easier for detectives in Braunschweig, around 15 minutes' drive away, to question Brueckner about the Madeleine case, as well as two others.
Keeping prisoners is expensive and under Germany's federal system the states are obliged to deal with their own prisoners rather than it being handled by a central judiciary.
German media says Brueckner received at least two criminal convictions from a Hanover court, one for forging documents in 2010 and another for theft in 2013.
Prosecutor Hans Christian Wolters addresses the media on the Madeleine McCann case
Madeleine was just three years old when she disappeared while on holiday in Praia da Luz in Portugal's Algarve region with her parents Kate and Gerry McCann
He split his time between Germany and Portugal from 2013 to 2015, prosecutors in Hanover have said.
Brueckner lived in the Algarve for much of the period from 1995 to 2007, and German prosecutors say he received a phone call from a Portuguese number around the time of Madeleine's disappearance in May 2007.
He made a living doing odd jobs in the area where Madeleine disappeared, and was also known to have burgled hotel rooms and holiday flats.
Weeks after the allotment search, authorities indicated they had been looking for digital storage devices, but Brueckner's lawyer accused them of 'desperation'.
Since taking the lead in the case earlier this year, German police have struggled to explain what evidence they have about Madeleine's disappearance.
Last week, a leaked memo revealed that Portuguese investigators were 'shocked' by the lack of concrete evidence after being briefed on the case against Brueckner.
Before that, there was confusion about whether German authorities had specific evidence that Madeleine was dead, as they initially implied they did.