A teacher who allegedly beat one student to death with a stick and injured three others in Shandong province had chronic depression, according to reports.

The incident took place on May 28 when the teacher, identified only as Li, was leading an after-school tutorial class at her home in Wulian county.

According to a report in China Youth Daily on Thursday, which cited an appraisal provided by the police, Li had diminished responsibility for the incident because she presented psychotic symptoms during the attack.

The appraisal was carried out on behalf of the police by an independent assessment team from a forensic medicine and science institute at the China University of Political Science and Law.

Wang Xinliang, the attorney hired by the family of the dead student, said a defense of “diminished responsibility” will allow the suspect to be given a mitigated punishment.

The local authorities said Li used to be a substitute teacher in her village but was dismissed in 2002. Since then, she made a living by tutoring from her home, teaching Chinese and math to students from the third to sixth grade.

He Zhaolong, the father of the dead student, told media in May that his 12-year-old son had been taking Li's classes for several years.

zhaoruixue@chinadaily.com.cn