Murder of Jenjira Ployangunsri

Jenjira Ployangunsri, a 23-year-old fifth-year medical student at the Faculty of Medicine Ramathibodi Hospital in Bangkok, was last seen alive on 26 January 1998. She had been in a relationship with Serm Sakhonrat, a second-year medical student at the BMA Medical College, whom she had met years earlier through church. According to the case record, Serm shot Jenjira in the head with an illegally owned .38 revolver at his apartment in the Phetchaburi Road area, killing her. He then dismembered her body with a kitchen knife, disposing of remains via the toilet and the apartment's septic tank, and discarded her skull, limbs, and bones in the Bang Pakong River in Chachoengsao Province. In the following days he visited a friend's house in Thonburi and his family home in Chon Buri Province, where he burned her clothing, and left her car in Nonthaburi Province.

Jenjira's parents reported her disappearance to police on 30 January and named Serm, who was questioned repeatedly over subsequent weeks. He gave contradictory statements and was subjected to polygraph testing, but police initially found no physical evidence. After tracking down witnesses, police took Serm into custody on 5 March 1998, at which point he confessed, though his account changed multiple times as investigators uncovered contradicting physical evidence, including a skull recovered from the river that was later confirmed through dental identification and DNA analysis to be Jenjira's, and human flesh matching her DNA found in his apartment's septic tank. The case marked the first use of forensic DNA analysis in a Thai murder investigation and brought public attention to forensic pathologist Porntip Rojanasunan, who assisted as a liaison between police and DNA experts.

At trial in 1999, Serm initially recanted his confession, alleging duress, but pleaded guilty after a bag containing Jenjira's belongings was discovered hidden at his friend's house. He was convicted of premeditated murder, unlawfully firing a gun in an urban area, destruction of a corpse, theft, and unlawful possession of a firearm, and was sentenced to death, commuted to life imprisonment due to his confession. The Court of Appeal upheld the sentence, additionally finding the murder was committed in a cruel manner. On appeal to the Supreme Court, Serm's defence argued the killing occurred in the heat of passion, but the court rejected this in October 2003, reinstating the original conviction and sentence, and issuing a widely quoted judicial opinion on the nature of love.

Serm served his sentence at Bang Kwang Central Prison, where he was regarded as a well-behaved inmate. Through five royal pardons, his sentence was reduced to thirteen years and five months, and he was released in December 2011 at age 35. While imprisoned he completed a law degree, though his application to the Thai Bar Association was later rejected due to his conviction. Serm maintained in later interviews that he discovered Jenjira was involved with someone else and killed her during a loss of control following a confrontation, though psychiatric evaluation found him competent to stand trial, and investigators considered the dismemberment likely an attempt to conceal evidence rather than evidence of a specific psychiatric condition.