SINGAPORE - A man who was of unsound mind when he attacked his father with a pair of scissors was acquitted of the offence and kept in safe custody at the Institute of Mental Health (IMH).

District Judge Ng Peng Hong said on Tuesday that IMH, rather than prison, was a more appropriate place to confine Mr Lee Jun Hong.

The 26-year-old is said to have used a pair of scissors to stab his father, Mr Lee Kok Keong, 56, in the back, causing a 4cm-long stab wound, on Sept 24 last year.

Deputy Public Prosecutor Kelly Ho said the victim and Mr Lee were alone at their home in Jalan Bukit Merah that evening watching a television show about a man who had killed someone and was pretending to be suffering from a psychiatric illness.

The older man was going to the kitchen when the younger man, who had been talking to himself, dashed towards his father.

He took a pair of scissors from the kitchen drawer and charged at his father, who turned and ran towards the kitchen toilet to hide.

He caught up with his father and stabbed the older man in the back before throwing the scissors on the floor.

He then followed his father into the toilet and punched the older man randomly. One of the punches landed near his father's right eye.

The older man managed to push the younger man aside and sought refuge at their neighbour's home. The police were called.

An IMH report stated that the younger Mr Lee was of unsound mind at the time.

So he was incapable of knowing that the nature of the act was wrong or contrary to law, the DPP said.

She applied for him to be put in custody under Section 252 of the Criminal Procedure Code.

His lawyer, Mr Favian Kang, said that the IMH was a more appropriate place for his client than prison. The lawyer said when the younger Mr Lee committed the offence, he thought his father was a "devil in disguise''.

While in remand, the younger Mr Lee heard and saw more things, and his condition worsened, said the lawyer. After he was sent to IMH, he was certified fit to plead seven months later.

Mr Kang said Mr Lee's parents support their son's stay in IMH as it would enhance his recovery and the treatment was better than in prison.

The maximum penalty for the offence is seven years' jail, fine, caning or any combined punishment.