Police on Monday started questioning schoolteachers in Kobe involved in the bullying of a 25-year-old male colleague, a source close to the matter said.

The police are questioning the teachers on a voluntary basis after a local education board said last month that the male teacher at Higashisuma Elementary School had complained of being bullied by four senior colleagues.

The education board said the three men and a woman in their 30s and 40s, who have all admitted they bullied the teacher, forced him to eat spicy curry and daubed some of it on his face, while saying they believed they were on good terms with the victim and did not know he had been in distress.

Following the bullying, the male teacher has been on leave since September with mental health concerns, and his lawyer filed a criminal complaint with local police on Oct. 1.

According to the source, the police have already interviewed the male teacher as well as others who witnessed the bullying.

A lawyer for the accused teachers, however, said one of them is claiming to have had no involvement in forcing the male teacher to eat spicy curry, despite having admitted to physically and verbally aggressive behaviors toward him.

The education board put the four teachers on leave starting Oct. 1.