The Mobile petrol station in Peakhurst where Gao Jin was fatally stabbed in 2003. Credit:Dean Sewell CCTV from the service station showed a few things. First, the taller of the robbers was unusually so - about 1.9 metres. Second, he had touched the sliding aluminium door with his hand on his way out. A DNA sample was taken but the preliminary result was weak, meaning it could not be used to identify the man. The CCTV also showed a car driving through the service station not long before the robbery, slowly and without stopping. The image was blurry so Revette had it enhanced, but this did not make much difference. He took it home to play it on a projector, to enlarge the image. "I don't normally take work home," he said, "but this case had got under my skin." On the projector he was able to see the vehicle had an arrangement of back lights unique to the Nissan Skyline. This might be handy if the vehicle had been the getaway car - and if they ever found a suspect with such a car. But, for the moment, it meant nothing. "We had no leads," Revette recalled. "We had absolutely no lines of inquiry." Soon after the robbery, a boarding house manager came into Burwood police station and said one of his lodgers liked to play with a knife and had boasted to other residents he had killed someone in a recent robbery that had gone wrong. Revette looked into the man's background and found he had a criminal associate who was very tall. He decided to begin electronic surveillance of the man using listening devices and phone taps. The initial results suggested the lodger was a sick and compulsive liar, with no connection to the robbery.

PhD student Gao Jin was fatally stabbed during a hold-up. THE MOBILE Revette had put a check on Jin's stolen mobile phone, so he would be told if it was used. Ten days after the robbery, it was, for 52 seconds at 3.39am. But it was used with a different SIM card. Police tracked down the owner of the card and discovered she lived 500 metres from the Mobil service station with her adolescent son, who this reporter will call ''Hakim'', because juveniles involved in criminal cases cannot be named. But was Hakim one of the robbers or just an innocent who had found the phone after they had discarded it? Revette figured it would be too risky to ask directly. If Hakim was involved, he might deny it and tell his colleagues the police were nosing around, making them more cautious. The detective decided to begin electronic surveillance of the young man. This meant removing surveillance from the man in the boarding house, as resources were limited. THE WIRE

It proved to be the right move. Police soon learned from their surveillance - which included a hidden camera - that one of Hakim's friends, another juvenile this reporter will call ''Ahmed'', had a criminal record, was 1.87 metres tall and owned a Nissan Skyline. They extended their surveillance to Ahmed and discovered he had quite a few friends who also had criminal convictions. Police put the electronics around these men, too, and after a lot of mind-numbing listening heard one say to his father that "the Turkish" had killed Jin. Among Ahmed's criminal associates was one with a father born in Turkey. The son's name was Mahmoud Houri and his parents had come to Australia from Lebanon in 1984, the year of his birth. At the time Gao Jin died, Houri was just 19 years old. Revette now had an idea who the three people in the robbery had been. He suspected Hakim had driven the getaway car while Ahmed and Houri committed the robbery, with Houri killing Jin. He figured Houri was capable of this because of another matter he had just been involved in. Three months after the robbery of the Mobil service station, Houri had struck again, trying to rob the Saint George Hotel, at Belmore. This time, too, it had gone horribly wrong, but mainly for him. He had put a gun to the security guard's head and told the man to hand over his own weapon. The guard had taken his gun from its holster but was trembling so much he shot himself in his other arm. In his confusion, he thought Houri had fired the shot, so he started to fire at Houri, who by this point was fleeing. Houri was hit five times in the lower back. When the paramedics arrived, they thought Houri was dead, but one stuck a finger in his sphincter - a standard test - and got a reaction indicating otherwise.

By the time Douglas Revette linked Houri to Jin's murder, Houri was a known armed robber, one with a bullet lodged in his spine. He could walk short distances with a stick but spent most of his waking hours in a wheelchair. Apart from the permanent damage to his spinal cord, he had had his spleen and left kidney removed during surgery and had been left with no sexual function and no urinary or bowel control. He was on bail for the Saint George Hotel robbery and avoiding court by deliberately infecting himself. GETTING PROOF Despite their strong suspicions and the "Turkish" reference on one listening device, all police had for firm evidence was another recorded conversation in which Houri said to Ahmed: "You were there that night when I told him, 'Don't use [the phone, it] could leave a clue." Presumably this referred to Jin's mobile phone, but it was not enough for a trial.

By now, Revette had talked to Hakim, the youngest of the trio, who had denied everything. His mother had given him an alibi, saying they were having a barbecue together when the service station was robbed. Revette considered approaching Ahmed and Houri, but there seemed little point. It was far more likely they would get lawyers, who would urge them to say nothing. Revette needed a way of breaking into the wall of silence around the three youths. He arrested Hakim and recorded his mother telling him in jail to lie to the police. Revette then told Hakim that before his matter went to trial, he was thinking of charging his mother with attempting to pervert the course of justice. This would probably put her in jail, as she was on a good behaviour bond for a previous offence. To reduce the chance of his mother being charged, Hakim agreed to plead guilty to the service station robbery, and give evidence against Ahmed. Police had achieved what was to be the beginning of the end. DNA

Revette had more work done on the DNA sample collected from the aluminium door at the service station and had obtained a stronger profile that tied it to Ahmed. But Ahmed had been a customer at the service station, raising the possibility he might have left the DNA on the door during a previous visit and not during the robbery. The service station taped over its CCTV footage every month, so police watched the footage for almost 30 days before the robbery, to check that Ahmed had not touched the door in that period. Further inquiries, one involving tests of aluminum surfaces and another a consultation with a DNA expert in New Orleans, established that the DNA sample could not have been left on the door more than 30 days ago. Revette confronted Ahmed with the DNA evidence, and with Hakim's statement implicating him in the robbery. Ahmed admitted he had been one of the robbers but said there had been no intention to harm Jin. He agreed to give evidence against Houri for the fatal stabbing. This - encouraging criminals to roll over on their associates - is how police solve many major crimes. Revette now had statements from two of the three robbers and finally knew what had happened on December 20, 2003. THE TRUTH The three robbers had indeed driven through the service station in the Nissan Skyline just before the robbery - to make sure Jin was alone. Houri had been high on ice (two grams a day) for the week before the robbery and during it. He killed Jin after noticing the silent alarm button had been pressed. (Apparently it remained half-depressed after being pushed.) He told the court, "I was under the influence of drugs and I just freaked out."

After the robbery, Houri and Ahmed dropped Hakim off at his home and gave him $50. "Is that all I get?" he said, so Houri gave him Jin's mobile phone, too, with strict instructions never to make a call on it. But Hakim did use the phone, 10 days later. He might not have been thinking clearly at the time: he was a heavy marijuana user and the number he called belonged to a dealer. Ahmed pleaded guilty and received a sentence of 12 years and eight months for his role in the murder. Houri was arrested at Roselands on October 13, 2005. When the police arrived he pulled the SIM card from his phone and swallowed it. Revette, helped by colleagues Sam Tinney and Chris Laird, carried him down the stairs of his apartment block in his wheelchair. Outside the premises Houri gave two fingers to the police photographer. He pleaded guilty just before his trial was due to start. The judge, sympathetic to the fact jail would be especially hard for him due to his physical condition, gave him a sentence of 18 years, with a non-parole term of 12 years and six months. It was only two years more than the non-parole term given to Ahmed, who had not stabbed Jin and had testified against Houri. Jin's wife was upset by the sentence, but Revette told her it was likely Houri would misbehave in jail and serve more than the non-parole period.

"There's no way he'll keep his nose clean," he said. Houri's record in jail was not good. He had been discovered hiding contraband in the frame of his wheelchair. At Parklea jail he was seen giving a map of the prison to a visitor, whom he asked to provide him with an escape kit. When confronted with the map by authorities, Houri leapt out of his wheelchair, grabbed the piece of paper, and ate it. In January 2009, during an argument with a fellow inmate, Houri cried out, "No one calls me a murderer!" and stabbed the man with a pair of scissors that were taped open. Two guards who tried to intervene were threatened with the makeshift weapon. Houri was charged with that assault but missed dozens of court appearances by claiming to be too sick to appear in court, even via videolink. This meant that for the past three years The Sun-Herald has been unable to publish this story about his earlier offences, in case such a publication might have influenced readers who would be jurors in the assault trial. However, this is no longer an issue. Mahmoud Houri died at the Prince of Wales ICU at 10.30pm last Tuesday. The immediate cause of death was cardiac arrest, but his body had been fatally weakened by the injuries from the 2004 shooting.

He was 27.