Police concluded that Choi Chung-rak planned the attack after finding that he prepared several weapons and a hand guard before stabbing 10 people at a large shopping complex in Incheon. He carried a kitchen knife, a utility knife, a hammer and scissors to the probation office for an electronic ankle-monitor appointment, but the entrance metal detector was switched off and failed to identify the weapons.
Staff had reportedly turned it off because frequent alarms caused noise and inconvenience, while the police said the equipment had not operated at least during that year. Police will notify the Justice Ministry about the security failure, although they said the detector’s nonoperation alone does not establish dereliction of duty by probation officers.