Investigators in Germany believe British girl Madeleine McCann was abused and killed shortly after being kidnapped.
Hans Christian Wolters, who is leading the investigation, has revealed police found information that the main suspect, Christian Bruckner, boasted about torture and destroying evidence with another paedophile online.
Speaking to the Times, Wolters said Bruckner talked about kidnapping, raping and killing a girl.
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During the conversation, he made threats about wanting to catch something little and use it for days".
When asked about getting caught, he reportedly said: "Meh, if the evidence is destroyed ..."
He then added: "Then I'll record maaaany videos/clips. I'll document in detail how she's being tortured."
German police said they came across this evidence when investigating the disappearance of Inga Gehricke, 5, which is a case that Bruckner has also been linked to.
Speaking about his theory about McCann case, Wolters said: "My private opinion is that he relatively quickly killed the girl, possibly abused her and then killed her.
"We believe our suspect committed further crimes, especially sexual crimes, in Portugal possibly but also elsewhere in Germany."
Meanwhile, satellite images taken shortly after McCann's disappearance appear to show the prime suspect's camper van parked just a mile away from her hotel and are being examined by German police, Britain's Daily Telegraph has learned.
Heriberto Janosch Gonzalez, a Spanish criminologist who works in computer science, was contacted by officers from Germany's Federal Criminal Police Office just hours after he sent them a picture he uncovered this week from early June 2007 — just weeks after the young girl disappeared.
The van, a distinctive white and yellow VW T3 Westfalia from the 1980s, appears to be parked near a run-down farmhouse where the suspect lived until late 2006 and could offer clues as to where Christian Bruckner went after McCann's abduction.
The farmhouse had been left "ramshackle with no sign of occupancy" in 2006, its British owner said.
Sitting at the end of a dusty dirt road, it is surrounded by hilly scrubland and has a number of deep wells close by, which Janosch Gonzalez said police should now search.
Speaking to the Telegraph, Janosch Gonzalez said he was confident the van belonged to Bruckner.
"The satellite images depend on the definition and perspective, so it was very difficult to do an exact analysis, but the measures and proportions, the location of the windshield, correspond well to a VW T3 Westfalia campervan," he said.
It came as a British ex-girlfriend of Bruckner's claimed he told her he had "a horrible job to do in Praia da Luz" the night before Madeleine disappeared. He told the woman who was not identified: "It's something I have to do, and it will change my life. You won't be seeing me for a while," according to the Sun.
Bruckner dated two British women while he lived in Prai da Luz, both of whom have reportedly given evidence to the police. It is also claimed that he told friends "just don't go there" when asked if he had anything to do with the disappearance
In the months after Madeleine's disappearance, the prime suspect turned up at a restaurant in a remote village 65km from Praia da Luz asking for a job.
There, he knew Nicole Fehlinger, a foster carer who looked after vulnerable German children.
On Tuesday, Fehlinger's father Dieter said: "If I had known then what I know about Christian now I would have killed him.
"When I first met him I was certainly suspicious of him."
He added that Fehlinger also had a young blonde daughter living there at the time Bruckner was in the area.
The news comes as British victims of sexual assaults in the Algarve were urged to contact police, after an Irish woman said that her rape could be linked to the man suspected of abducting Madeleine McCann.
An Irish woman who was raped in a nearby town in 2004 said that her attacker, who has never been found, spoke English with a German accent and had blonde hair and piercing blue eyes — all of which match the description of Bruckner.
The German paedophile has been convicted of raping a 72-year-old American tourist at a luxury beachfront villa in Praia da Luz in 2005, and has a long history of sexual assaults against women and children.
Bruckner is being investigated in connection with the disappearance of five children – including Madeleine, 3, who went missing in the Algarve in 2007.
- additional reporting Telegraph UK