SEOUL, The driver of a car that barreled into pedestrians, killing nine, in central Seoul this week has been booked for investigation and police are considering seeking an arrest warrant for him, officials said Tuesday. Police also plan to request a forensic analysis of the sedan in connection with the 68-year-old's claim that the vehicle suddenly accelerated out of control when it darted in the reverse direction on a one-way road near Seoul City Hall, plowed through a sidewalk guardrail and struck people Monday night. Six of those killed died at the scene, while the three others were taken to a hospital in cardiac arrest and later pronounced dead. Those killed included four colleagues from a nearby bank and two employees of the Seoul city government. Four others were also injured, including the driver who broke his ribs. He was not under the influence of alcohol at the time of the crash, officials said. Chung Yong-woo, a senior police officer at the Namdaemun Police Station, said the driver was booked for investigation on charges of negligent driving resulting in deaths and injuries. Police will consider seeking an arrest warrant for him, he said. Chung said there was no evidence of sudden unintended acceleration, aside from the driver's claims. Even if sudden unintended acceleration was the cause, the charges leveled against the driver will not change, he added. The official said police plan to request an investigation of the driver's vehicle by the National Forensic Service to verify his claim. The car was moved to the forensic service Tuesday morning to undergo analysis, which typically takes one to two months. The suspect was identified as a bus driver with a 40-year driving career. Police said he did not try to flee the scene, and no trace of alcohol or drugs was found in tests. But a blood sample was taken for additional investigation, given the gravity of the case. "The perpetrator is having difficulty speaking at the moment," Chung said. "Upon hearing the doctor's opinion, we will call him to the police station or visit him at the hospital for questioning." As of Tuesday morning, police were reviewing witness statements, CCTV footage and dashcam camera data to establish the exact circumstances of the crash. Police also plan to question the driver's wife who was in the sedan at the time of the accident. "Police will conduct the investigation as promptly as possible to prevent any destruction of evidence," Chung said. Source: Yonhap News Agency