Natascha Kampusch detective 'was killed because he knew too much' Colonel Franz Kroll of the Vienna police died from a gunshot wound to the head outside his Graz home in June 2010, six months after Kampusch had escaped the clutches of Wolfgang Priklopil, her kidnapper. His service pistol was found at his feet and an apparent suicide note outlining family and work problems led to an official investigation concluding he had committed suicide. But his brother Karl, who has always disputed the suicide verdict, now says new research by Professor Eduard Leinzinger, director of forensic medicine at Graz University of Medicine, undermines the official explanation. Mr Kroll has claimed that his brother had told him he was "on to something big" as he led the police investigation into the Kampusch case but added that he had come under pressure to lie. Then the Vienna police suddenly closed the case and the "two dozen indicators" of an accomplice Colonel Kroll had found were never followed up. Although off the case, it appears Kroll had carried on investigating it, and recording details in a note pad that disappeared when he died. "A file that my brother always had with him vanished after his death, and the suicide note, which wasn't even in his handwriting, only appeared a few days later," his brother told the Austrian press. When I tried to raise the matter I was arrested and my house searched. Mr Kroll said he hoped the new forensic evidence would trigger a parliamentary inquiry into his brother's death and the Kampusch case. Miss Kampusch has always maintained that no one else other than Priklopil was involved in her kidnap and years of imprisonment. She has also said the speculation surrounding the death of Kroll was "wounding" and "prolonged her trauma."