Brueckner has been on trial in the central German city of Brunswick since February on three counts of rape and two counts of child sex abuse allegedly committed in Portugal between 2000 and 2017.
The charges are unrelated to the Madeleine McCann case, in which Brueckner was sensationally revealed as a suspect in 2020.
Chief prosecutor Ute Lindemann described Brueckner as a “dangerous psychopathic sadist” and called for him to be placed in preventive detention after serving his sentence as there was a “high degree of certainty” that he would reoffend.
The statute of limitations was found to have expired on one of the rape allegations, meaning it was not included in the prosecution’s sentencing demands.
However, Lindemann called for a sentence of 13 years in total for the remaining two counts of rape and two years in total for the two counts of child sex abuse.
Brueckner, wearing a grey jacket over a white shirt, remained composed as Lindemann read her closing statement.
In one of the rape cases, prosecutors accuse Brueckner of entering the holiday apartment of a woman aged between 70 and 80, tying her up and sexually assaulting and beating her.
In the other, he is accused of entering a young Irish woman’s apartment via her balcony while she was sleeping, threatening her with a knife and raping her several times.
The Irish woman, who testified during the trial, had been subjected to a “truly terrible” ordeal and was still suffering from post-traumatic stress from the “extremely brutal” attack, Lindemann said.
Brueckner is also accused of exposing himself in front of a 10-year-old German girl on a beach and an 11-year-old Portuguese girl at a playground.
Brueckner’s defence team has raised major doubts about the evidence against him and in July won a bid for an arrest warrant against him to be cancelled.
That move was a technicality because Brueckner remains behind bars, serving a sentence for the rape of a 72-year-old American tourist in 2005.
But Brueckner’s lawyer Friedrich Fuelscher said at the time the court’s decision was a “clear sign that the defendant will be acquitted”.
Prosecutor Lindemann on Wednesday criticised the court over the decision, saying she had the impression it had “already agreed on an acquittal”.
She also rejected doubts raised about the reliability of one of the witnesses, Helge Busching, who testified based on video footage he claimed to have seen of one of the crimes.
Busching gave a “high-quality testimony”, Lindemann said.
The prosecutor also described the content of notebooks seized from Christian B. and used as evidence in the trial, detailing the similarities between his sexual fantasises and the alleged crimes.
Three-year-old Madeleine went missing from her family’s holiday apartment in Praia da Luz in Portugal’s Algarve region in May 2007 while her parents dined at a nearby tapas bar.
Despite a huge international manhunt and global media attention, no trace of her has been found and no one has been charged over her disappearance.
When German authorities revealed Brueckner was a suspect in 2020, it was a major bombshell for the investigation -- one of the highest-profile missing persons cases in history.
Even then, Brueckner already had a host of previous convictions for crimes including sexual assaults of children and drug trafficking.
The charges in the Brunswick trial came about as a direct result of investigations into the “Maddie” case, according to prosecutors.
German prosecutors have not charged Brueckner over Madeleine McCann’s disappearance, although they have said they have “concrete evidence” that Madeleine is dead.
If acquitted in the Brunswick trial and not charged in the “Maddie” case, Brueckner could be free as soon as the spring of next year, according to Fuelscher.
