For me, it's a study of the old fashioned way of police(RX) that beats confessions and the modern way with psy. tech. to break criminals.(GE) RX was so used to it that I was angry when he beat his son and had to be stopped to retract fake confession. When his son was released , and if he had came home most likely he would have forbidden that evening run. So poor parenting that resulted in broken communication filled with broken promises ,lies and mistrust ended with broken people.
The killer has suppressed emotions against RX ,that scene at the hospital bed, said it all. He was so full of jealousy and envy against him for having a well-mannered Son and a pretty capable wife while he has an unloving cold daughter, bossy and fierce wife and No Son. He was also eaten up with bitter resentment and anger of RX having a tall and imposing police figure while he was nondescript and impotent. RX should have realized he was fake and insincere, for why should a poor struggling hawker give free meals even when his daughter had not run away. People who curry favor either want something in return or like TH, behind scornful, for fooling the police. He came to gloat and sneered by eating the lipstick for getting away with killings and mastermind killing of RX's son, all along.. His ego trips him. as the police were at a dead end for 18 years.
Policing a community is not superficial knowing them but has to combine with straightening kinks for if RX had follow-up by asking that kid why he kept hitting at lamplights, the killer would have been caught earlier. It's much like doing a poor parenting job, as a happier home, happier society with less criminals. Criminals like TH who were numb and insensitive to others pains and sufferings as he was brought up by fisherman grandfather who often beat fishes to death and an abusive father, hence insensitive to his daughter, TC, hurt and silent pain at being locked up to study the whole time with no freedom and no friends, cycle of unhappy home continue. A happy family is being whole again just like TC, LK's mother and Nurse Tong, all having 2nd chances. Unlike GE, burdened with past mistake, unable to move on and no time for marriage.
The final question, who was at fault ,it's the mentor and student has to live with scars. That's my understanding of the ending so if there is S2, hope to see GE happily married and mentoring a policeman with issues which GE can handle it very well.
