German prosecutors want to take charge of the investigation of an Algarve rape linked to Madeleine McCann suspect Christian Brueckner.
They have requested the court files and evidence held in Portugal relating to the unsolved 2004 rape of Irish woman Hazel Behan.
Investigators want to do their own work to see if they can prove Brueckner committed the vicious sex attack on holiday rep Ms Behan at her home in Praia da Rocha, a half-hour drive east of Praia da Luz.
DNA samples, including blood and semen collected from the crime scene by Portuguese police at the time, have been destroyed, leaving question marks over whether a successful prosecution can be mounted.
However, a DNA profile is understood to have been obtained before the shock destruction of the potentially crucial samples on the orders of Portuguese prosecutors.
Mother-of-two Ms Behan waived her right to anonymity last month to say she believed the masked man who targeted her in her Algarve apartment could have been Brueckner.
She said the intruder had a distinctive mark on the top of his right thigh like the German paedophile.
The sex attacker removed her clothes with scissors and gagged her with cloth.
Brueckner was convicted late last year in Germany of raping an American OAP in September 2005 in Praia da Luz, the same resort Madeleine vanished from in May 2007 as her parents ate in a restaurant nearby.
A hair found at the villa, said to have been taken from the bedclothes Portuguese investigators failed to test, helped secure his conviction and remains on file.
Last week Sky News reported Portuguese police had reopened their investigation into Ms Behan's unsolved rape following its mothballing years ago.
However, well-placed sources say the current state of play is that Portuguese authorities have been asked to consider an official request from Germany to send the case files, including any DNA evidence, to prosecutors there so they can mount their own investigation and see if Brueckner is the mystery rapist. No decision would be made until September after the judicial recess.
"Any ruling to let Germany take the lead in this case would have a closely-related legal precedent," a source said.
"The Praia da Luz rape Brueckner was convicted of was a crime committed in Portugal but prosecuted in Germany because of Portugal's statute of limitations.
"The time limit applies to the earlier rape Brueckner has been linked to.
"There is a time limit in Portugal on the prosecution of even the most serious crimes, including homicide and kidnapping."
Respected Portuguese website Observador echoed news of the German push to move the Ms Behan case forward on Saturday by claiming: "Sources have confirmed to us that, just like in the American OAP rape case, they are going to forward the evidence they have in the Hazel Behan rape case to German police.
"That's because their hands are tied as it's too late to investigate in Portugal. It's going to be the Germans who will investigate whether Brueckner could be responsible."
The McCanns' family lawyer Rogerio Alves spoke about the 15-year time limit on Portuguese prosecutions in a documentary on Thursday, saying police had just 22 months to nail the prime suspect in Madeleine McCann's abduction.