Christian Brueckner managed to cultivate his image as a so-called 'playboy', donning a pinstripe blazer and driving a vintage Jaguar.
But behind this glamourous portrayal was a warped predator who dealt drugs, committed burglary's and hid a disturbing history of child sex abuse.
This week, the German paedophile who is the prime suspect in the abduction and murder of Madeleine McCann broke his silence for the first time since being identified in the ongoing investigation.
The 44-year-old convicted paedophile, who is currently serving seven years in jail for the rape of an elderly woman in the Algarve, called the investigation a 'scandal' in a handwritten letter and called for the resignation of authorities for "persecuting an innocent person".
Brueckner was first convicted of abusing children at the age of 17 in 1994, where he later moved to Portugal the following year. He spent more than a decade in Praia De Luz, the resort town in the Algarve where Kate and Gerry McCann took their three children on holiday.
Over his decades-long spree, the career criminal is believed to have notched up as many as 17 separate convictions, while enjoying a nomadic life across Europe.
Growing up in Wuerzburg, Bavaria, Brueckner committed his first burglary when he was just 15.
He fled to Portugal after serving a two-year juvenile term for abusing a six-year-old girl in a playground and exposing himself to a nine-year-old girl when he was 17.
The German newspaper Bild quotes him as saying: "We didn't know anything about Portugal. We went to Lagos because we liked the name so much. We had a tent with us and camped in the wild."
Renting a farmhouse in Monte Judeu, near Praia da Luz, Brueckner was seen speeding around country roads in his 1993 Jaguar XJR6 and would flirt with tourists who flocked to the picturesque holiday hotspot.
Speaking to the Mirror, his English ex-girlfriend said: "Chris could be very, very charming, very funny and very smooth in the way he talked.
“He always dressed nicely, held the door open, that kind of thing. He drove the nice car – the black Jaguar – was very gentlemanly and spoke properly."
Secretly, however, he was embarking on a crime spree that involved dealing cannabis, drug-trafficking and allegedly stealing laptops and passports from rooms at the nearby resort.
During one sickening burglary, Brueckner blindfolded and raped a 72-year-old American woman at her Algarve apartment, beating her with a metal pole.
The 2005 attack was videotaped and the footage was discovered by friends, who had broken into his house to retrieve the camera.
However, one of the witnesses said they destroyed the film in disgust and did not report the contents to police until more than a decade later.
According to evidence heard at Brueckner's eventual trial over the rape, the witness recognised the beast in the film after he took his mask off.
He said: "Then the man sat on the bed and pulled the mask off his face. I thought: That can't be!"
The witness told the court he had also seen a second film that showed a younger woman tied naked to a wooden beam and claiming she had been raped, while Brueckner sat on a sofa.
The elderly woman told investigators of the terrifying 15-minute ordeal: "I felt that he enjoyed torturing me."
In April 2007, Brueckner moved out of his home and into a VW Westfalia campervan.
A month later, Madeleine went missing from her family's holiday apartment in Praia da Luz, just days before her fourth birthday.
Her parents, Kate and Gerry, had put her and her siblings to bed in the flat before joining friends for dinner at a tapas restaurant nearby.
Police had Breuckner in their sights within five days and staff at the resort were shown his picture and name to see if they recognised him.
Goncalo Amaral, who led the initial probe, confirmed in an interview that a German paedophile had been identified in 2007 as a potential suspect.
Making the comments in 2019, he did not name him but said the man was serving a prison term in Germany – just like Brueckner.
However, Amaral said his detectives found nothing to suggest the German was involved in Madeleine’s abduction.
Brueckner moved back to Germany the month after Madeleine went missing, travelling between Portugal and Italy over the next decade.
During this time, he faced further convictions for drug offences, including a 19-month sentence over a crime that involved "narcotics in large quantities".
In 2016 he was jailed for 15 months for "sexually abusing a child in the act of procuring himself and possessing child pornography".
The following year, he was once again sentenced to 15 months in prison for the sexual abuse of a child.
After his release, he became homeless and attempted to flee to Milan.
However, he was extradited to Germany from Italy under a 2018 arrest warrant that cited a drugs conviction and sent to prison in Kiel in Schleswig-Holstein, where he is currently being detained.
A year earlier, the witness who saw footage of his 2005 rape attack had gone to police, who found enough evidence to build a case against him.
Brueckner was sentenced to seven years in jail over the attack in 2019 and lost an appeal against the ruling last August.
It was not until last year that he was identified as the chief suspect in the Madeleine McCann case.
Police said that significant information had emerged after investigators made an appeal in May 2017, the 10th anniversary of Madeleine’s disappearance.
Central to the new investigation is the discovery of a 30-minute phone call that places Breuckner in Praia da Luz just hour before the three-year-old is feared to have been snatched.
Cops have seized his campervan, which was sold in 2015, to examine it for clues.
German tabloid Bild reported on Monday that it had obtained a letter penned by Brueckner.
Writing from prison, he said: "Charging an accused is one thing. Something completely different - namely, it is an unbelievable scandal - when a public prosecutor starts a public campaign for prejudice before a court case is opened.
"Freedom of expression is not a basic right so that everyone can say and write what they want. Freedom of expression does not protect the majority.
"It protects the minority. It does not protect the most logical, most convincing or most popular views, but rather the outsider position.
"I call on the Brunswick public prosecutors (Hans Christian) Wolters and (Ute) Lindemann to resign from their offices.
"Both are proving worldwide through my arbitrary condemnation in the past and through their scandalous pre-denial campaign in the present against me as an innocent person that they are not suitable for an office as a lawyer for the honest and trusting German people and you bring shame onto the judiciary."
Earlier this month, prosecutor Hans Christian Wolters told the Mirror he was "pleased" with how the case has progressed and suggested it could be solved in months.
Wolters said prosecutors still had unanswered questions, however.
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