The horror of the high-profile case, affected SGT Ng emotionally making him more determined to help solve the riddle and bring the culprits to justice. And even after cracking the case, he helped solve another two murder/kidnappings in Yuen Long and Cheung Chau.

"That all these cases were solved could probably be the most precious retirement gift of all for me," the 47-year-old said, adding he was due to hand in his Police Warrant Card next month.

SGT Ng joined the Force in 1973, serving in various crime and anti-triad units, with many of the cases he handled throughout his near three-decade career headlining newspapers. Listening to SGT Ng discussing his old cases sounds almost like a lecture in criminology or the script to a Hollywood blockbuster. But the seasoned sleuth said his most haunting memory was of an armed robbery in Tsim Sha Tsui in May 1985.

"Armed with high-power guns, the criminals were a real menace and more than 100 shots were exchanged with police. People were running for their lives and one of our officers was nearly killed," he recalled.

Another memory which makes him shudder was his spotting of an armed robber he had arrested years earlier, on an MTR station platform.

"I guessed he had served his jail term, but his eyes were as vicious as before. The guy never took them off me and he came closer and closer. The world seemed still and I could hardly breathe. I feared a showdown but he just came up and said 'hi, don't you recognise me? I'm now doing business'."

Breathing a sigh of relief, SGT Ng chatted briefly with the reformed bandit before wishing him good luck in his new life.

Despite seeing many heartbreaking cases during his career, he said he always stuck to his principles of good policing and to strive for goals.

"Sport, movies and travelling have been very helpful in alleviating pressures of the job. And I also enjoy reading books on religion to have a better understanding on what's going on in this world," he said.

"Although there may not have been a satisfactory ending for every case I dealt with, I tried my best in the pursuit of justice and I feel good about myself."