A special police team investigating the Itaewon crowd crush is trying to find out why the chief of the Yongsan Fire Station failed to swiftly issue a response alert on the night of the tragedy.

The special headquarters said on Wednesday that Yongsan fire chief Choi Seong-beom is subject to an investigation based on internal reports, bodycam footage from that night and transcripts of communication between fire officials.

The chief, already under investigation on charges of professional negligence resulting in death, is now facing scrutiny for not responding even after receiving a police request for a joint response to the scene, believing that it was not necessary.

The investigation team believes that the fire department failed to issue response alerts in a timely manner, with the first-stage alert at 10:43 p.m. on October 29, some 30 minutes after the crush, the second-stage alert about a half hour later and the third-stage at 11:48 p.m., some 90 minutes after the crush.

Municipal regulations dictate that a third-stage response alert be issued in the event the number of casualties exceeds 20 people. Even as dozens were already in cardiac arrest and receiving CPR at the crush site, the response alert remained at the second-stage.