Somkid Pumpuang was born on January 7, 1964, in the Thung Song district of Thailand. When he was eight years old, his father left him to live with his uncle. During this time, Somkid began to steal. One incident involved him stealing a teacher's bicycle, which led to his expulsion from school.

Around the age of 14 or 15, Somkid's uncle helped him find work at a sawmill in the Thung Song district. His job involved handling rubberwood. However, his uncle soon discovered that he was stealing money from his employer. This led to Somkid being kicked out of the job and moving back in with his father in Trang province.

Living with his father was difficult. They often got into arguments, and Somkid continued to steal. Eventually, he had to leave the village after an attack by a group of teenagers. This incident forced him to travel around the country.

From January 30 to June 21, 2005, Somkid Pumpuang committed a series of murders across different provinces in Thailand, killing five women. He often used strangulation to kill his victims. In some cases, he tied them up and held their heads under water. The murders typically took place in hotels, and he would steal items, like mobile phones, from the women.

His first victim was Warunee Phimphabutr, a café singer, who he killed on January 30 in Mukdahan province. He tied her hands behind her back with her own bra and drowned her in a bathtub. He stole a gold necklace, her mobile phone, and a motorcycle. The second victim was Phongphan Sapchai, a masseuse, whom he strangled in a hotel in Lampang province on June 4. He then murdered Patcharee Amatanirand, another café singer, on June 11 in Trang province, using a wire to strangle her. A week later, on June 18, he killed Porntawan Pangkabutr at a hotel in Udon Thani province.

The final murder was of Sompong Pimpornpirm, also a masseuse, in Buriram province on June 21. Six days after this last killing, Pumpuang was arrested while attempting to take another woman to a hotel. Police found a stolen cellphone from the final victim on him. After linking him to all five murders, he was charged with five counts of murder and theft.

During his trial, he pleaded guilty to four of the murders, excluding one. This led to an automatic life sentence. Over the years, his sentence was reduced due to clemency, and he was released from prison on May 17, 2019.

After his release, he began a relationship with a 51-year-old housekeeper named Rassamee Mulichan. On December 15, 2019, neighbors reported hearing them arguing, and later the same day, Rassamee was found dead in their apartment. She had been wrapped in a blanket and tape. An investigation revealed that she died from suffocation, and witnesses identified Pumpuang as the last person seen leaving the apartment.

Four days later, he was found and arrested at a train station. During questioning, he admitted to strangling Rassamee after an argument. This led to his conviction for murder, and he was sentenced to death. The case raised concerns about the justice system, especially regarding the pardons that allowed him to be released previously. The couple who reported his whereabouts received recognition for their actions in helping capture him.