A dispute over donations led to a brawl that left catering safety officer Tay Eng Soon, 53, dead after his attacker punched his face twice.
Mr Lim Keow Chye, 49, also kicked Mr Tay's stomach when the latter, who worked for flight service provider Sats, fell to the ground.
In an inquiry into Mr Tay's death yesterday, State Coroner Marvin Bay found that Mr Lim had inflicted fatal injuries during the violent assault at a coffee shop at Block 303, Anchorvale Link in Sengkang at around 10pm on July 8, 2015.
The coroner also said that Mr Lim had "perpetrated the unlawful killing" of Mr Tay.
He added: "Efforts to arrest Mr Lim were thwarted as (he) was found to have left Singapore shortly after the event and his whereabouts remain unknown to date.
"Police have also enlisted the assistance of the Royal Malaysia Police to help apprehend Mr Lim, and there had been no credible leads to his whereabouts thus far."
Mr Tay, his wife and two friends had gone to the coffee shop to eat and drink. This included consuming alcoholic beverages.
Mr Lim, his older sister and three friends were at another table, drinking beer.
The coroner said: "Investigations including a statement recorded from Mr Lim's sister further reveal that Mr Lim had an ongoing dispute with Mr Tay and his wife over donations which Mr Tay's wife had collected for a temple in Thailand, and where Mr Lim's mother had placed donations."
Closed-circuit television footage from a camera at the coffee shop was played in court yesterday.
It showed Mr Lim standing near Mr Tay's table aggressively at 10.09pm. Mr Lim seemed to exchange angry words with them and gesticulated wildly with his hands.
Two minutes later, he marched over to Mr Tay, who was seated. Mr Lim suddenly grabbed the latter's neck before punching his face twice.
Coroner Bay said that after the blows, Mr Tay appeared severely disoriented and collapsed to the ground. Mr Lim then walked towards him and kicked his stomach once before walking away.
Mr Tay's wife, Madam Ng Lee Kiam, managed to lift her husband and sat him on a chair. But the father of two sons remained unresponsive.
An ambulance rushed him to Tan Tock Seng Hospital and he was pronounced dead about 2-1/2 hours later.
Following an autopsy, forensic pathologist Lee Chin Thye found that Mr Tay died owing to bleeding in the subarachnoid space, which is the area between the brain and the tissues that cover it. The space is also the area where cerebrospinal fluid circulates.
Coroner Bay said that there was clear evidence of foul play, adding: "There is, from the scene, forensic and documentary evidence, a direct causal link between Mr Lim's actions and Mr Tay's collapse and subsequent demise. The investigation has not implicated any other individual in Mr Tay's death."