There had been early warning signs the accused Nazi sympathiser would do something terrible. In fact, one of his favourite activities after work as a pipelayer with Cairns City Council was stealing sticks of gelignite from his employer and blowing up gum trees. He also tested his ability in making pipe bombs. "Karl Kast had no real criminal history to speak of but he had a real interest in explosions," local historian Jack Sim said yesterday. Kast, a German ship deserter who was released from a prison camp in Australia during World War II and took on local citizenship, found it hard to secure work and developed a "paranoid view of Australia".

He showed a remarkable memory - he was apparently able to draw an entire to-scale map of the nation's eastern seaboard including dams, ports and railway without prompting - but felt isolated. One day, working in Cairns, Kast fell into a trench onto a hard steel pipe. The 30-year-old started to make claims about severe back pain and visited local doctors, but accused them of discrimination after they failed to substantiate his injury complaints. I think he had intention to commit a great act of terror on Wickham Terrace that day He refused to work, claiming he could not raise his arms past his waist and all his toes on his right foot had turned black and green, and demanded a pension for the rest of his life.

Kast, who spoke to authorities with "utter contempt", travelled to Brisbane's famed "street of doctors" - Wickham Terrace - to find a medic who would support his claims. In today's parlance, it would be known as doctor shopping. But fresh x-rays found nothing. "This just added to Karl Kast's paranoia that he was a victim of a system that was against 'Krauts', against 'New Australians', and against him," Mr Sim said. "Karl Kast would begin to do the rounds of doctors." Even a well-respected and sympathetic orthopaedic surgeon, Dr Arthur Meehan, who promised to ignore everything the other doctors had said and look at his case afresh, concluded the pain he claimed to suffer was all in the mind.

"You're all liars," Kast protested, threatening to kill all of the doctors who had challenged his story. The angry patient returned to Wickham Terrace on December 1, 1955, bearing a .38 calibre revolver and a satchel containing 12 pipe bombs he had made in the bedroom of his Woolloongabba home. The first stop was Dr Michael Gallagher's practice on the second floor of Wickham House, which still stands today despite Kast's unsuccessful attempt to blow up the building. Kast fired bullets into the doctor's right forearm, the right side of his chest and his leg. "It is to do with spines," Kast said, when challenged about his behaviour in front of horrified onlookers, before heading back downstairs.

Miraculously, Dr Gallagher survived the gunshots. As he was leaving Wickham House, Kast laid down a number of bombs and a lit candle in the foyer area before fleeing to the next building. Mr Sim said experts believed the firepower would have been enough to bring down the entire building, had a racehorse trainer not suspected something was awry and hurled the explosives out on to the street. The bomb broke the windows of a passing cab and smashed the bitumen as shrapnel from the explosion hit a nurse in the eyebrow. The nurse had earlier thought someone careless had left a lit cigarette in the foyer.

Karl Kast, meanwhile, was heading to Ballow Chambers where a number of other doctors on his hit list worked. The first man he killed was Dr Andrew Murray, a well-mannered man who had moved from England with his wife and children. "He walked up to Dr Murray and shot him straight in the head as he sat at the desk," Mr Sim said. He then visited Dr Meehan, whom he also shot dead in cold blood. Kast was to make one other stop before his murderous rampage came to a close.

He walked into the practice of John Lahz, wearing a light blue safari suit with a striped tie. He menaced the waiting patients before politely asking a woman whether she would mind his satchel for a couple of minutes. But when Kast strode into Dr Lahz's office and levelled his gun at him, something unexpected happened. Two nurses stepped in front of the doctor to protect him. Kast hesitated long enough to provide the doctor time to run away to safety. "The remaining bombs in his satchel, he produced them, he ended up going in to Dr Lahz's room, he went down on the desk and he laid down the remaining bombs that he had in his possession and they exploded," Mr Sim said. "They tore Karl Kast into pieces but he was still alive, so he took out the revolver and shot himself."

The explosions could be heard across town in Woolloongabba - the sight of destruction everywhere and onlookers were in hysterics. Mr Sim said people sometimes thought Australia was immune to terrorism-style attacks, but forgot about incidents like Karl Kast's rampage. "I think he had intention to commit a great act of terror on Wickham Terrace that day."

