Madeleine McCann detectives are planning to return to Portugal for 'one final push' in their investigation before the New Year, reports claim.
Investigators want to head back to Praia de Luz, where the British three-year-old was snatched on a family holiday thirteen years ago.
A source working on the case said detectives are desperate to head to the Algarve to find fresh leads on prime suspect, Christian Brueckner, after 'hitting a wall' in recent weeks.
The 43-year-old, who has child pornography and rape convictions, is currently serving a drugs jail term in Germany.
He lived near the Praia da Luz resort where the British toddler vanished in 2007.
Brueckner’s lawyer Friedrich Fuelscher says his client is innocent.
Reports claimed the investigation is being scaled back ahead of the New Year due to a lack of fresh evidence.
But a source close to the investigation told The Sun: “German officers believe there are areas of the investigation into [Christian B] and his time in Portugal which would benefit from having boots on the ground.
“Most specifically there are unanswered questions about [Christian B's] movements in the days and weeks after [Madeleine] vanished.
“German officers also think witnesses still living in Portugal could hold vital clues."
The newspaper claims the German police officers' desire to head to the Algarve is due to a breakdown in relations with their Portuguese counterparts.
According to The Sun, the two forces have differing views on whether Brueckner was involved in Maddie's disappearance.
The German detectives will need to generate fresh leads to gain permission to investigate in Portugal again, the newspaper reports.
The Mirror reported over the weekend that German prosecutors fear they will never bring Brueckner to court.
The prosecutor leading the inquiry into Brueckner’s alleged links to Maddie's disappearance, Hans Christian Wolters, said there was no “forensic evidence.”
Mr Wolters, who is leading the probe in Germany, added that other clues investigators had were “not enough to get an arrest warrant”.
Brueckner was named as a suspect in June amid claims of “strong evidence”.
German prosecutors revealed they were certain Maddie was dead, in a bombshell claim.
But Mr Wolters said that without new clues, Brueckner will never be quizzed over the Maddie case.