For more than 30 minutes on Dec 16, Peter Chua Teck Choon terrified MRT train commuters on a north-bound train towards Dhoby Ghaut.
Dressed like a samurai, the 39-year-old martial arts instructor had drawn a katana - a samurai sword with a 75cm sharpened blade - to ward off three TransCom officers trying to apprehend him.
The officers, who handle public transport security, had asked Chua to leave the train while they were in a north-bound train from City Hall to Dhoby Ghaut.
Instead of complying, Chua turned aggressive, pushing one of the officers and shouting vulgarities.
The officers warned him about his behaviour.
That was when Chua swung his sword in a threatening manner at the three officers.
Yesterday, Chua pleaded guilty to voluntary causing hurt, criminal intimidation and using criminal force on a public servant.
He was sentenced to seven weeks' jail.
Four other charges, including one of outrage of modesty, were considered.
He was accompanied to court by his mother, Madam Tan Yoke Lan, a 59-year-old cleaner.
The incident started at about 12.20pm when Chua boarded a bus to Paya Lebar MRT station.
Before alighting, he unsheathed his Katana sword and poked its tip at the stomach of a 37-year-old commuter, leaving a red mark on the man's skin.
At the train station, Chua jumped a fare gate and boarded a train bound for City Hall MRT station.
TransCom officers intercepted Chua at Bugis MRT station and tailed him.
Chua alighted at City Hall MRT station and switched lines to a train heading towards Dhoby Ghaut.
Realising he was being followed, Chua became agitated.
He hurled vulgarities at the officers and pushed two of them before unsheathing his sword.
Chua then put his sword back and alighted at Dhoby Ghaut station, where he took another train back to City Hall MRT station, where he alighted.
He was eventually arrested at Jalan Pisang near Sultan Mosque in Bugis.
Chua's lawyer, Mr Louis Joseph, asked for a lenient sentence, saying that his client was remorseful. He added that Chua had mental issues.
Deputy Public Prosecutor Siti Adrianni Marhain said Chua had a history of poly-substance abuse and was diagnosed as having "substance-induced psychosis". (See report above.)
Nevertheless, she sought a custodial sentence because Chua had caused fear and had a clear disregard of the law by trying to evade arrest.
Ms Siti Adrianni said: "In an hour, he (Chua) had committed seven different offences."
District Judge Ng Peng Hong said he could not give much weight to Chua's mitigation plea because the psychosis experienced by Chua during the incident was self-induced.
Meanwhile, Chua's mother told reporters her son had not told her about his intention to plead guilty yesterday.
She said: "Since young he has been obedient... He didn't rob or steal. I'm sad he has to go to jail."
Substance-induced psychotic disorder
Substance-induced psychotic disorder refers to abnormal behaviour caused by taking drugs, said Dr Thomas Lee, a psychiatrist at the Resilienz Clinic.
He said: "It refers to the way a person talks or acts. A person could hear voices, hallucinate, or have untrue beliefs such as feeling that everybody is plotting against him.
"Such paranoia is commonly seen in people who have taken street drugs."
These include methamphetamine, also known as Ice, cocaine or LSD. The state of intoxication could last quite some time.
Psychiatrist in private practice, Dr Lim Boon Leng, told The New Paper that there are several ways that a psychotic state can be induced.
Certain drugs, such as LSD, can cause hallucinations almost immediately, even if the abuser does not overdose on it.
He said the most common form of drug-induced psychosis are from substances such as cannabis, which can continue to have effects on the human body for up to six months - long after the drug has left the body.
Chua has a history of poly-substance abuse, which means he used multiple illicit drugs at the same time.
Dr Lee said this would amplify the effects of the drugs.
Crimes under psychosis
A 33-year-old man with a psychotic disorder hit his mother repeatedly on the head, and taped her mouth shut. All this after she quizzed him about his bad attitude on the phone.
In a 2½-hour long ordeal, he grabbed her hands, slapped her and punched her on the head. He then pulled her by the hair into his bedroom, sat on her and continued to punch her. He also pulled her mouth sideways to stop her from shouting for help.
The man was jailed 26 months, but was spared caning due to his psychotic disorder.
A Turkish national at Changi Airport was waiting to catch a flight to Istanbul when he spread the word that a plane getting ready for take-off would blow up.
He then attacked an airport auxiliary police officer who tried to calm him down. The police had to use force to subdue him. About two days before he arrived here from Australia, the man had taken amphetamine, methamphetamine and cannabis, which gave him hallucinations and made him delusional. He was fined $1,000 and sentenced to a month in jail.
A man went on a rampage at home, swinging a 30cm-long chopper and an axe while claiming he had seen "people" at his rented flat.
After accidentally injuring himself, he dashed out of the house - bare-bodied and carrying the chopper and axe. He was later charged in court and taken to the Institute of Mental Health (IMH) for psychiatric assessment.
The man developed a high fever and was taken to Changi General Hospital where he died the next day.
This article was first published on July 17, 2014. Get The New Paper for more stories.