The murders, which took place in their Woodlands flat in Singapore, were supposedly committed due to Teo and his wife arguing with each other about their financial difficulties.

[6] The Woodlands family murder case was considered one of the most significant familicides (including the Chin Swee Road child death) in Singapore in recent years.

Teo was experiencing difficulty in managing his family's finances, and did not pay Zi Ning's school fees for months.

Teo and Choong, in view of their financial troubles, initially wanted to abort the child in November 2016, but decided to not do so after some counselling.

When Teo was brought to trial for the murder of his wife and daughter, he stated that during the argument, Choong belittled him for being a useless husband.

Teo later called in the afternoon through a payphone, saying that he had been driven out of the house by Choong after an argument, and tried to prevent his family and in-laws from visiting his flat in Woodlands.

During the evening, Gordon, the eldest of the Choong family's three adult children and only son, appeared at Teo's flat after failing multiple times to contact his sister.

[18] Forensic pathologist George Paul later tested the corpses and confirmed that both Zi Ning and her mother died from either strangulation or smothering.

[22] Many people, including PAP member of Parliament Vikram Nair from Sembawang GRC, came to the funeral to offer condolences to the bereaved family and the victims.

He was represented by leading criminal lawyer Eugene Thuraisingam, and the three-men prosecution team was led by Deputy Public Prosecutor (DPP) Han Ming Kuang (the other members were Dillon Kok and Ng Jun Chong).

Turning to Zi Ning, she was at the time watching television and playing with her toys, and she was not taking part in the arguments, hence she could not be responsible for the provocation.

He said that Teo was able to make a choice to take his wife's life as he wanted the family to escape the financial burdens and also to not let Zi Ning be alone without love after her parents' deaths.

[34] Their affectionate messages with each other showed that the couple was optimistic in spite of their difficulties, with Teo looking forward to his job and paying off the debts, and Choong planning to go back to work once their son turned two.

[35] After closing submissions were made on 5 July 2020 (a month after Singapore ended its circuit breaker measures), the High Court reserved its judgement until 12 November 2020.

He stated that Teo's claims of depression did not match to his behaviour before, during and after his crimes as he was able to sleep regular hours, still surfing the Web and Youtube and watching pornographic materials after murdering Choong and Zi Ning, and even meticulously thought of ways to mask the deaths as suicidal and hide the truth of the deaths from his family and in-laws.

Also, even if he was provoked and calmed down, Teo continued to strangle Choong as he, from his account, wanted to kill the family to not let them get burdened by his debts.

The other person was Ahmed Salim, a Bangladeshi painter who killed his Indonesian girlfriend Nurhidayati Wartono Surata (aged 34) at a Geylang hotel on 30 December 2018, two days before his 30th birthday.

Justice Judith Prakash, who delivered the verdict, stated that the High Court was correct to identify that Teo did not suffer from diminished responsibility based on his post-killing behaviour and attempts to hide traces of his crime.

Having accepted the major points of the lower court's judgement, Justice Prakash and her fellow four judges thus disapproved Teo's appeal and further condemned him to hang for Zi Ning's and Cheong's murders.

[48] Thuraisingam confirmed that his client will appeal to the President of Singapore Tharman Shanmugaratnam for clemency as a final recourse to avoid execution.

[49] In December 2023, Teo Ghim Heng was one of the 36 death row inmates who filed a legal motion to challenge the newly-enacted Post-Appeal Applications in Capital Cases Act (Pacc Act), which was designed to manage the last-minute appeals made by death row prisoners who exhausted all avenues of appeal.

Teo and his fellow plaintiffs argued that the new law was discriminatory against death row inmates and it would stall the last chances of the convicts' access to justice, which may lead to an unfair legal process.

However, 11 days after the appeal was filed, Justice Dedar Singh Gill found there was no reasonable cause of action and dismissed the motion, as the LASCO was "perfectly entitled to adopt or change its policy regarding its provision of legal aid", and there could have been multiple reasons for LASCO to not assign lawyers for such convicts, such as the need to allocate resources to aid new defendants who were facing trial and appeal and deter possible abuse of court processes.

The judge also stated that the lack of representation from LASCO in post-appeal applications did not deprive the accused persons of their right to life or personal liberty, which was especially so since all the plaintiffs in this case were already convicted and sentenced at this stage, and also exhausted their appeals against conviction and/or sentence, and their rights to access to justice were not violated by the lack of free legal representation, given that they still had the entitlement to engage lawyers on their own accord in any post-appeal applications.