German investigators have revealed they want to retest a mystery saliva sample found in the apartment where Madeleine McCann went missing.
Forensic tests in Portugal found no DNA match to the new suspect, who's known as 'Christian B'.
But German authorities believe their scientists should carry out their own checks as the sample could contain vital evidence.
Sky's crime correspondent Martin Brunt's is in Portugal, and says the implication is they think they can do it better:
"Given the row that has developed between the German and the Portuguese police over the past two weeks, accusations about various things flying from one side to another, I understand that Portuguese police have initially said they're not going to send it."
The development follows yesterday's report by numerous German and British outlets that prosecutor Hans Christian Wolters had written to the McCann family to inform them that he now had 'concrete evidence' that German paedophile 'Christian B' killed Madeline McCann.
These reports were flatly denied by the McCann family, who stated they didn't receive a letter from German police.
However, the saga took yet another dramatic turn last night when German prosecutors reiterated that a letter had been sent to the family.
Hans Christian Wolters is still calling for more information about 'Christian B':
“We think the suspect has committed more crimes possibly against British people, Irish and Americans. We think there are more victims of sexual crimes [committed by Christian B].”
