Police said Wednesday they have arrested a 39-year-old man over the death of his 1-month-old baby son in Konosu, Saitama Prefecture.

According to police, the man, who has been named as Yuji Obaku, was investigated after his son Ryuto was taken to hospital and diagnosed with brain damage in early March, NTV reported. Staff at the hospital advised police that the boy’s injuries may have been caused by violence.

Following a police investigation, Obaku was accused of seizing the infant by the head and slamming him into a futon mattress. Police say Obaku also shook the boy repeatedly.

Obaku and his 27-year-old wife already had two children before Ryuto, police said. It is currently unknown whether Obaku’s other children also suffered from assault or mistreatment.

During police questioning, Obaku was quoted by police as saying: “I got angry because he wouldn’t stop crying.”

Japan Today