ByThe Good Samaritan, who remains anonymous, noted the killer car’s number and handed it to the security guard of a building near the accident, site. The number proved to the clinching evidence.An auto driver, who was the sole witness to a hit-andrun in Goregaon last month that left a woman battling for her life, has helped cops crack the case.The car driver, who was caught in a CCTV camera knocking down the woman and then dragging her some distance before speeding away, was arrested on Saturday. The arrest would not have been possible without the help of the auto driver who had the presence of mind to note down the car’s number when the accident happened.The auto-driver, however remains unidentified as he had noted down the number on a piece of paper and handed it over to the security guard of a nearby building.Rajmati Jain, a housewife, had stepped out on SV Road on December 8 when a speeding Innova hit her.The impact was so strong that Jain was flung nearly 20 feet. The Innova driver, however, made no attempt to stop or slow down and ended up dragging her a fair distance after the car hit her a second time.The Innova’s driver Tej Bahadur Giri was arrested after the cops got in touch with the car’s owner and he revealed that on December 8 when the accident took place Giri was the only one in the car. The owner, whose identity the cops have not revealed, had lied about the damage to the car, saying it had hit a tempo. Jain, meanwhile, continues to battle for her life at Bombay Hospital.Senior Inspector S D Wadke said it was not an easy case to crack as the registration number (MH04 CU 8815) provided by the auto driver, the only clue they had. “However, when we checked with the RTO, this number turned out to be that of a truck,” he said. “We realised that the auto-driver in all the hurry had made a mistake. We then decided to get the list of all vehicles with their registration number ending 8815,” Wadke said. They also procured all registration numbers of Innovas registered in Thane as MH04 belongs to Thane RTO.In all, the cops got nearly 20 numbers. The next step was to call owners of these vehicles. When the owner of this car was contacted, he confirmed his car (MH04 CJ 8815) meeting with an accident on December 8. “It took us nearly a month to crack this case. The CCTV footage was poor. In fact, we could not even decipher the car registration number from the footage,” said Wadke.