The eight-year police investigation failed to explore fully many of the key questions about the mysterious crime. Ms Kampusch, 18, was seized on her way to school when she was aged 10, bundled into a van and held captive in the home of Wolfgang Priklopil, 44, a technician. She escaped last August and Mr Priklopil decapitated himself on the same day by lying in front of a train. Max Edelbacher, the retired police commander who supervised the investigation from 1998 to 2002, admitted that he could see some disparities in the case. “There are always three levels of truth in a criminal inquiry: what actually happened, what the police find out and what evidence is accepted in court.” More than 160 boxes of police files remain secret but four central questions remain unanswered.

• Was there an accomplice during the original kidnapping in March 1998 and during the subsequent 8½ years of captivity?

  A 12-year-old girl who went to the same Vienna school as Ms Kampusch claimed to have witnessed the abduction, which according to her involved two kidnappers. At the time, the witness gave an accurate description of the white Mercedes van used by Priklopil to snatch Ms Kampusch and drive her to his house near Vienna.

  The witness, now 20, repeated her claims of a second man during recent police questioning after Ms Kampusch’s escape. Major-General Gerhard Lang, of the Austrian police, said they had found no evidence of an accomplice.

• What drove Priklopil to commit the crime?

  No profile of Priklopil was ever commissioned. Major-General Lang told The Times: “We will never know his motives because he is dead and he never told Ms Kampusch about it.” Police ignored German magazine reports, apparently based on sources close to the investigation, that claimed Priklopil had links to the Viennese sadomasochistic underworld. “We have no evidence that Ms Kampusch was involved,” Major-General Lang said.

• Did Priklopil know any of the family of Ms Kampusch?

  Police appeared to have discounted the testimony from neighbours claiming that he knew her mother, Brigitta Sirny. A neighbour claimed to have seen Priklopil fixing the fuse box in the shop then run by Mrs Sirny. Investigators also appear not to have fully followed up reports that Priklopil was a regular at the snack bar that was visited by Mrs Sirny and frequented by Ms Kampusch’s father, Ludwig Koch.

• What was the exact nature of the relationship between the kidnapper and his victim?

  Police are using elaborate privacy laws to withhold information about the strange rapport that developed between them. Ms Kampusch’s lawyers have already admitted that she went on a skiing holiday with Priklopil. Many of Priklopil’s neighbours claim to have seen them together and some even assumed that they were a couple. “We will not now or at any time give any public statements regarding sexual matters in relation to Ms Kampusch,” Major-General Lang said. “We assume that he wanted to have someone to communicate with.” One of the main hindrances in the investigation before Ms Kampusch escaped was the early assumption that she had been killed. The police were looking for a corpse rather than a living captive.

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