For more than a month, Madam Chua Kee Ching agonised over what to do.
"It was the hardest decision of my life but reporting my son to the police was the only way I could make him come to his senses," the 52-year-old production worker says in Cantonese.
"He is my only child. I didn't want his future to be ruined if he ended up with a police record."
Her son, then 17, had gone on a rebellious path in secondary school.
She says: "Do you know, he actually scored an aggregate of 240 for his PSLE? My son went to a good school, but somehow, when he was in Secondary 2, something just went wrong."
And she is certain it had nothing to do with her being a single parent.
"My husband died (of cancer) when my boy was eight. If anything, I felt that his father's death made him grow up overnight," says Madam Chua with a wry smile.
"He'd help with the household chores when I was at work, and he kept promising me he'd study hard so we could both have a better life."
To reward her son for his good results, Madam Chua even saved up to take him to the Gold Coast in Australia.
But things started to go downhill after her son turned 14.
"Suddenly, he was an angry teenager. Nothing seemed to please him. He'd come home late at night, still in his school uniform and smelling of stale cigarettes," she recalls.
"He'd just ask me to get out of his room and then slam the door shut. Because he was at that age, I controlled my urge to scold him and tried to advise him instead. I had to keep my worries at bay."
Then one day, the school called to tell her that her 15-year-old would be suspended for punching his physical education teacher.
Madam Chua says: "I was so shocked. I couldn't believe that my 'guai guai zai' (good son in Cantonese) had turned into a stranger."
During the two weeks of suspension, her son returned home only twice - the first time was to stuff some clothes into a paper bag. Five days later, he turned up to demand $300 from her.
"At first I refused. I kept asking him what he needed it for, but he just said, 'You can give me the money or you can regret it later if you don't'," says Madam Chua.
In the end, she gave in.
"Later on, when I thought back about the early days, I realised that it was I who had allowed my son to go further astray. I should have stood my ground," she says.
Her son stayed out of trouble when he returned to school and she thought "closing one eye" would help ease the tension.
POLY OVER JC
He did well enough to get into a junior college but insisted on going to a polytechnic.
"I was happy that he did well and I didn't mind. I thought he had got over that phase," she says.
Until one day when she was cleaning her son's room. She had picked up his backpack and had accidentally dropped it on the floor.
"I heard a clang so I opened it. To my horror, there was a long kitchen knife and the blade was wrapped with a piece of newspaper.
"My hands were shaking, my heart was beating so fast. I couldn't believe what I was holding in my hand."
Yet she did not confront her son.