A man in his 20s who stabbed a teacher in a high school in Daejeon last Friday is suspected to have committed the crime due to mental illness.

According to the Daejeon Daedeok Police Station on Tuesday, although the teacher worked at the high school the suspect had attended, he had never been the suspect's homeroom teacher.

Based on questioning of the suspect's former schoolmates and mother as well as colleagues of the victim, the police found no evidence to back the suspect's earlier testimony that he had been harassed by the victim in school.

His mother in fact testified that her son has shown symptoms of delusion, with a diagnosis of schizophrenia and depression between 2021 and 2022 that led to a rejected recommendation by a doctor to seek inpatient treatment.

Investigators plan to verify the suspect's testimony and analyze his crime through profiling while also intending to question the victim, who is recovering in intensive care.

The incident came on the heels of recent stabbing rampages in Seoul's Sillim area and the Gyeonggi provincial city of Seongnam, which together have resulted in at least two deaths and over a dozen injuries.