MADELEINE McCann suspects Christian B of being accused of the 2004 rape of a woman in the Algarve.
German officials have announced that the 45-year-old sex offender will be charged with brutally attacking Irish tour representative Hazel Behan three years before the British toddler disappeared.
Der Spiegel reported that prosecutors “conclude” their rape investigation early next year.
Miss Behan, who was 20 at the time of the attack, came forward in June 2020 after learning of her previous convictions.
He is currently serving a seven-year sentence for raping an American pensioner in 2005.
German prosecutors have yet to reveal what evidence they have implicating him in the case, and his lawyer declined to comment.
Christian, a German national, is currently serving a seven-year sentence in Germany for raping a pensioner in 2005 and lived in the Algarve between 1995 and 2007.
He took up odd jobs in the area where Madeleine disappeared and is known to have robbed hotel rooms and holiday apartments.
Officials have named him the prime suspect in Maddie’s disappearance, but he strenuously denies the allegations.
She disappeared from a holiday apartment, aged three, in Praia da Luz, Portugal, in 2007.
Portuguese police files on Miss Behan’s case seen by German media claim there are similarities between her case and the attack on the 72-year-old woman.
Miss Behan described how a masked man climbed onto the balcony of her flat in the early hours of the morning.
She said a knife was held to her throat before the man tied her up and gagged her before repeatedly raping her over a period of four or five hours.
The assailant then threatened to kill her before fleeing through the balcony and leaving her to bleed.
Last month, we revealed that Christian B once told a friend that he had murdered a former girlfriend.
The man, called Aberle, said Christian B, 44, admitted to having “accidentally killed” the woman while drunk.
Aberle told cops in 2010 – around the time prostitute Monika Pawlak, 24, was mutilated and stuffed into two trash bags.
Christian B was a suspect in the Hamburg murder but was never charged.
Details emerged during a summit between German and Portuguese cops to review the Maddie case.