"It was subsequently established that he had died of natural causes," police told Channel NewsAsia.
According to reports, Ng, who is the next-door neighbour, had not seen the deceased for about a week. On Monday night, he realised that there was something wrong and raised the alarm.
"It was Monday, just past midnight," Ng told Channel NewsAsia on Wednesday. He said that his neighbour lived alone with a dog. "I was coming back. The dog barked at me as usual, but I never thought of anything."
On Tuesday, the 60-year-old retiree called his neighbour as they had not seen each other for a week or so. "That was the first time that I reached the voicemail," he added. "He was a guy who would call me back, no matter how."
When he again called the deceased in the afternoon, he got the voicemail again. "I was thinking, something is really wrong," he said. When he tried knocking on the door, the dog barked at him again.
Ng said that this was unusual as his neighbour would always be with his dog in his room with the air-conditioning on. So, it was impossible that the dog would be out in the living room for so long alone.
Following this, Ng called the man's sister and later his family members called the police. The authorities entered the flat with the help of a locksmith.
"They didn't want to damage anything in case he was hospitalised or went somewhere without informing anybody," Ng said. "But the first thing they saw was him lying on the floor near the door."
Ng described his neighbour as a a "great" animal lover who would feed every stray cat in the neighbourhood for "breakfast, lunch and dinner".
"If he was still alive, he'd still be feeding them," he told Channel NewsAsia.