SINGAPORE - A man who spent seven years in the Institute of Mental Health (IMH) for killing his brother-in-law has been sentenced to life imprisonment for another murder.

Yaacob Mohamed Yatim, 58, pleaded guilty on Thursday (April 19) to stabbing and causing the death of Mr Abdul Rashid Mohd Nenggal, an acquaintance he had fallen out with.

A court heard that Yaacob was charged with the murder of his brother-in-law following a domestic dispute in 1999. But this was withdrawn as Yaacob was found to be of unsound mind due to epilepsy and he was detained at IMH from 2000 to 2007.

But on the evening of May 3, 2015, Yaacob committed yet another killing, that of Mr Rashid, 48.

They had fallen out previously as Yaacob, who worked as a cleaner, had misplaced the $45 that he was supposed to pass to Mr Rashid. Their relationship remained bad though Yaacob eventually passed Mr Rashid the money.

Things got ugly on May 3 when they ran into each other at a coffee shop in Geylang. Mr Rashid approached Yaacob and punched him in the face. Mr Rashid was pulled away by the coffee shop's owner but continued to shout at Yaacob.

Yaacob went back to his food but remained angry. He later tried to take a pair of kitchen scissors from the coffee shop's ayam penyet stall but was stopped by staff.

Yaacob got a knife with a 13cm-long blade from a nearby Sheng Siong supermarket, returned to his table at the coffee shop and called his mother to ask for her forgiveness.

Soon after, Mr Rashid approached Yaacob, in a bid to talk out their dispute peacefully. Yaacob replied that there was nothing to talk about and stabbed Mr Rashid in the back.

Mr Rashid ran but Yaacob chased him to a slip road, where Mr Rashid fell. Yaacob kicked him in the face and left. The coffee shop owner rushed out and asked if Yaacob knew what he done, to which Yaacob replied: "Now he knows who I am."

Mr Rashid was later pronounced dead at Tan Tock Seng Hospital and Yaacob was arrested the next day.

In his mitigation plea, Yaacob's lawyer Anand Nalachandran said his client was not the initial aggressor and tried to avoid Mr Rashid. He said Yaacob led a "simple and solitary existence", living only with his mother. His wife and daughter had both died - the child was only seven when she died of leukaemia.

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

Yaacob could have been sentenced to death for his charge of murder.