The Toa Payoh ritual murders took place in Singapore in 1981. Two children, a nine-year-old girl and a ten-year-old boy was murdered, purportedly as blood sacrifices to the Hindu goddess Kali. The murders were masterminded by Adrian Lim, a self-styled medium, tricked scores of women into offering money and sexual services in exchange for cures, beauty, and good fortune. Two of the women, Tan Mui Choo and Hoe Kah Hong, became his loyal assistants. A rape charge was later filed by one of Lim's targets, and he decided to kill children to derail their investigations. The trio were arrested after the police found a trail of blood that led to their flat.
The 41-day trial was the second longest to have been held in the courts of Singapore at the time. The trio were eventually sentenced to death. These murders shocked the public in Singapore; the case was closely followed and remained prominent in the Singaporean consciousness for several years. The actions and behaviour of the three killers were studied by academics in the criminal psychology field, and the rulings set by the courts became local case studies for diminished responsibility.