Police investigating the deadly car crash that killed nine people in downtown Seoul earlier this week said Wednesday they will speed up the probe as soon as the injured perpetrator's physical condition improves. The Seoul Namdaemun Police Station said it has asked the National Forensic Service (NIS) to scrutinize the perpetrator's sedan to ascertain whether his claim of sudden unintended acceleration as the cause of the crash is true. An NIS analysis of a vehicle's event data recorder (EDR) usually takes one to two months, the station said. Considering the seriousness of the case, however, the analysis period is expected to be shortened, it said in a media briefing. Surveillance camera footage shows a Hyundai Genesis sedan driven by the 68-year-old man, surnamed Cha, went against traffic about 200 meters after leaving a hotel near Seoul City Hall at 9:27 p.m. Monday before striking many pedestrians and two vehicles, crossing an intersection and stopping near City Hall Station. The police said the number of people injured from the car crash has increased by one to seven, as a pedestrian was rushed to a hospital without being reported to officers on the scene. Cha himself was hospitalized with broken ribs. Some experts have raised the possibility of the driver's carelessness or inattention, rather than sudden unintended acceleration, citing many circumstances, including the fact that the vehicle eventually stopped by itself. Jung Yong-woo, a Namdaemun officer in charge of the probe, said it has been confirmed that Cha's car began speeding from the entrance of the hotel after coming out of its underground parking lot, though he declined to comment on the speed at that time. He said Cha's wife, in her 60s, who was in the car at the time of the accident, was questioned as a witness Tuesday. "She made a statement to the effect that the brakes did not work," Jung said. He also declined to disclose the content of the car's dash cam video. Reversing their previous announcement of skid marks left on the scene, pol ice also said there were no skid marks. They said they had mistaken traces of engine coolant leaks for tire marks. Skid marks can serve as a crucial clue in traffic accident investigations as they can be used to calculate the speed of a vehicle at the time of an accident and determine whether the driver attempted to brake before a collision. Meanwhile, the officer denied some media speculation that the accident may have been triggered by a quarrel between Cha and his wife. Source: Yonhap News Agency