SINGAPORE - On the anniversary of the day his father abandoned the family as well as his enlistment, a 20-year-old took a foldable knife and a wet wipe with him on his nightly jog.

Surajsrikan Diwakar Mani Tripathi became angry after he tripped and fell during his run, and decided to attack a stranger who jogged past him.

On Thursday, Surajsrikan, now 22, was sentenced to life imprisonment and 15 strokes of the cane after he pleaded guilty to a charge of murder in what prosecutors said was a "senseless" killing.

Surajsrikan admitted he stabbed and slashed Mr Tay Rui Hao, 38, an assistant manager at a sports apparel store, near a bus stop in Punggol Field at 11.08pm on May 10, 2020.

At 11.17pm, Mr Tay called 995 and said: "I've been stabbed many times." 

An ambulance took him to Sengkang General Hospital, but he later died from his injuries.

The charge of murder with the intention of causing fatal injury carries the death penalty or life imprisonment and caning.

Prosecutors told the High Court that they would not object to life imprisonment, but sought 24 strokes of the cane. The defence pleaded for no caning to be imposed.

In sentencing, Justice Dedar Singh Gill said the sentence will not erase the memories of the painful episode but hoped it could provide some sort of closure for the victim's family.

The court heard that May 10 was a significant date for Surajsrikan.

His father abandoned his mother while she was pregnant with him on May 10, 1999, two months into their arranged marriage, said his lawyer Edmond Pereira.

Surajsrikan enlisted for national service on May 10, 2018. Following an incident where he smashed communications equipment with a hammer in October that year, he was downgraded and discharged.

On the night of May 10, 2020, which was during the circuit breaker, Surajsrikan and Mr Tay left their respective homes for their regular runs.

"Bad memories associated with the date caused the accused to be frustrated and angry," said Deputy Public Prosecutor Andre Chong.

The prosecutor said Surajsrikan took along a Singapore Armed Forces-issued Swiss Victorinox Trailmaster knife and a wet wipe.

Mid-run, Surajsrikan fell near bus stop number 65559 in Punggol Field, and paced around for five to 10 minutes to work off his anger.

At 11.08pm, Mr Tay jogged past him.

Overcome with anger, Surajsrikan unfolded the knife and chased after the victim.

Upon catching up with Mr Tay, Surajsrikan stabbed him in the back.

As Mr Tay rolled forward to face his assailant and tried to sit up, Surajsrikan repeatedly slashed his arm, chest and abdominal area.

Surajsrikan then ran off, kept the knife in his pocket and cleaned his hands with the wet wipe.

He wandered around the neighbourhood for the next 1½ hours and threw the soiled wipe away before returning home at about 12.30am.

Surajsrikan was eventually traced through police surveillance camera recordings, which showed him wandering around the neighbourhood with the knife in his hand.

He was arrested at his home on May 16, and the knife, which he washed with hand soap, was found in his bedroom cupboard.

An autopsy found that Mr Tay died from a slash wound on his right forearm that cut a main artery, and a stab wound in his chest that collapsed his lung.

Mr Tay's blood was found on the knife as well as on Surajsrikan's shoes.

A psychiatric assessment found that Surajsrikan had severe social anxiety disorder, obsessive compulsive disorder and dyscalculia, which is a learning disability in mathematics.

The symptoms were found to have "crippling effects" on his life.

A report from the Institute of Mental Health said the significance of the date exacerbated Surajsrikan’s chronic feelings of anger and was the primary psychological driver for his actions.

In sentencing arguments, DPP Chong said Surajsrikan killed senselessly, simply to vent his anger over his own circumstances. 

“He brutally stabbed the deceased, who was entirely unknown to him, and who was simply going about his own business,” said the prosecutor.

Mr Pereira said Surajsrikan was a troubled youth who had immense difficulty in living his life due to stressors that triggered his anxiety and phobias.

Surajsrikan dropped out of Northlight School - a school for students with difficulties handling the mainstream curriculum - after one day due to anxiety, he said.

During national service, he felt overwhelmed having to work in a confined space with others.

Mr Pereira added that since his remand, Surajsrikan has been placed in a cell by himself due to his social anxiety disorder, and has been prescribed medication for his disorders.

“Our client wishes to apologise to the victim’s family for their irrecoverable loss,” said Mr Pereira, adding that Surajsrikan is deeply remorseful for what he has done to the victim and the pain and hardship he has caused the family.