Police on the 2nd carried out a search and seizure at the Daejeon headquarters of the National Information Resources Service (NIRS). Police are investigating the cause of the NIRS fire that brought down government computer networks.
The Daejeon Metropolitan Police Agency said it has been conducting search and seizure operations from 9 a.m. that day at four locations, including NIRS and three related companies, on suspicion of professional negligence causing fire. Police are said to be securing documents related to contracts and work.
Earlier, police booked four people on suspicion of professional negligence causing fire: one NIRS official, two officials from the site company for the battery transfer construction, and one official from the work supervision company.
NIRS explained that on the night of the 26th of last month, while turning off the battery power and cutting cables before transferring the lithium-ion batteries that were on the fifth floor to the basement, sparks flew from a battery for an unknown reason.
NIRS had been pursuing a project to separate the batteries from the servers to prevent server damage in the event of a battery fire. Police are focusing on whether the battery transfer work proceeded according to procedure and whether residual current blocking on the batteries was properly carried out.
Workers carried out the separation work without sufficiently discharging the batteries. Lee Jae-yong, head of NIRS, said at a question session on pending issues at the National Assembly's Public Administration and Security Committee the previous day, in response to a question from Ko Dong-jin of the People Power Party, who presented the "lithium battery separation and relocation guidelines" from two leading domestic battery manufacturers stating that the state of charge (SOC) must be reduced to 30% or less when separating lithium batteries, that "(the state of charge when separating the batteries) was about 80%."
Police believe the main power supply was cut off before the work. However, because there were other auxiliary power supplies, they judge that further verification is needed regarding the exact work timing and whether power was cut. To determine the cause of the fire, police commissioned the National Forensic Service to examine six batteries presumed to be where the fire first started and tools found at the scene.