SINGAPORE - A 51-year-old driver, who suspected that his wife of 21 years was having an affair, stabbed her repeatedly with a kitchen knife after she rebuffed him when he woke her early in the morning to talk about their "marital dispute".

After killing Madam Faridah Senin, 41, the mother of his three children, Rosdi Joenet called the police to report a murder, breaking down in tears over the phone.

On Monday (March 7), Rosdi was sentenced to nine years' jail after he pleaded guilty to a charge of culpable homicide, not amounting to murder, for killing his wife on Nov 17, 2012, at their Jurong West flat.

Madam Faridah, a security officer, suffered 18 knife wounds, of which two to her chest were fatal injuries.

Rosdi was diagnosed by a government psychiatrist to be suffering from a delusional disorder of the jealous subtype, a condition that impaired his mental responsibility for his actions.

His lawyer, Mr Abraham Vergis, told the High Court that his client was a loving husband until he began having delusions, six months prior to the offence, that his wife was being unfaithful.

He believed that she was seeing a man who drove a BMW and tried to get his daughter and his wife's co-workers to spy on her for him.

Deputy Public Prosecutor Wong Kok Weng told the court that Madam Faridah denied having an affair.

But the couple's relationship soured to the point that they were sleeping in separate rooms - Rosdi slept in the study while Madam Faridah slept with her mother in the master bedroom.

At about 5am on Nov 17, 2012, Rosdi woke up and found that his mother-in-law, Madam Siti Khatijah Md Bederan, was in the kitchen.He woke his wife up to discuss their problems, but was chased out with angry words.

He returned, armed with a knife that had a 20-cm long blade, and locked the door.

Hearing her daughter's screams, Madam Siti demanded the door to be opened but Rosdi told her he was in a "discussion" with Madam Faridah, who was heard begging him not to kill her.

Rosdi later emerged from the room, saying that he had killed his wife and had "reasons" for doing so. By then, his daugher and two sons had been awoken by their mother's screams.

Madam Siti called the police after seeing her daughter motionless on the floor, with blood on her shirt. A blood-stained knife was on a cabinet next to her.

Rosdi also called the police, saying: "Murder. I am the husband. My wife. I am unable to say anything now."