He killed his brother-in-law almost 20 years back but the charges were dropped because he was deemed to be of unsound mind and was instead sent to the Institute of Mental Health (IMH). But he has taken another life and will spend his life in prison for murder.

Yaacob Mohamed Yatim, 58, pleaded guilty yesterday to stabbing and causing the death of Mr Abdul Rashid Mohd Nenggal, an acquaintance he had fallen out with.

A court heard that Yaacob had once been charged with murdering his brother-in-law following a domestic dispute in 1999. But Yaacob was found to be suffering from epilepsy and of unsound mind. The charge was withdrawn and he was sent to IMH from 2000 to 2007.

On the evening of May 3, 2015, Yaacob took another life. He ran into Mr Rashid, 48, at a coffee shop in Geylang.

They had fallen out with each other in the past. Yaacob had once been entrusted with passing Mr Rashid his salary but had misplaced it instead. According to Yaacob's lawyer Anand Nalachandran, the amount was $45, which he paid Mr Rashid back the same day. Their relationship, however, soured.

They got into a dispute once again at the coffee shop and Mr Rashid punched Yaacob. Mr Rashid was pulled away by the coffee shop's owner.

Yaacob seethed as he ate his meal. When he was done eating, he went to one of the coffee shop's stalls and tried to take a pair of scissors there, but was stopped by the staff. He then went to a nearby Sheng Siong supermarket to buy a knife with a 13cm-long blade before returning to the coffee shop, where he called his mother to ask for her forgiveness.

Soon after, Mr Rashid approached Yaacob to talk about their differences but Yaacob said there was nothing to talk about and stabbed him. Mr Rashid tried to flee but Yaacob chased him to a slip road, where Mr Rashid tripped and fell. Yaacob then kicked him in the face once and walked away.

When the coffee shop owner rushed out to check on the commotion, he ran into Yaacob, who was walking towards him with the knife.

Mr Rashid was lying on the road. He was later pronounced dead at Tan Tock Seng Hospital.

Yaacob was arrested the next day.

In his mitigation plea, Mr Nalachandran said that while Yaacob's actions were wrong, he did not start the fight. He added that Yaacob led a "simple and solitary existence" with a small social circle and that his wife and daughter are dead. Yaacob lived with his mother.

Mr Nalachandran asked for life imprisonment for Yaacob. The prosecution did not object.

Yaacob could have been sentenced to death for murder.