Yoo Young-chul was born on April 18, 1970, in Gochang County, South Korea. He grew up in an environment marked by poverty. This background had a lasting impact on his life. In 1992, he got married and welcomed a son into the world. However, his personal life did not unfold smoothly.

From September to November 2003, Yoo Young-chul began his series of murders by targeting wealthy senior citizens. He broke into their homes and used a hammer to bludgeon them. To make the scenes look like robberies, he staged the crime scenes. However, no money was taken, which raised questions for the police investigating the crimes. As the investigation progressed, Yoo shifted his focus to female masseuses.

In January 2004, Yoo was briefly arrested for a minor theft charge but was released after two days. Starting in March 2004, he called prostitutes to his home in western Seoul. After having sex with them, he would murder them, dismember their bodies, and bury them in the mountains near the city. Police later found 11 of Yoo's victims' bodies in the mountains behind Bongwon Temple.

During questioning, Yoo confessed to killing 19 people. Later he admitted to an additional murder, a 44-year-old male street vendor. On 19 July 2004, he revised his total number of confessed murders to 26. His list included some victims who did not fit his previous patterns of targeting wealthy seniors or masseuses. This suggested that there might be other unreported victims.

Days after this confession, Yoo also acknowledged that he had killed a young woman in Imun-dong after pretending to be a police officer. He admitted to cannibalism, stating he had eaten the flesh of some of his victims, although this claim lacked any evidence.

Yoo was arrested on 15 July 2004 while meeting employees from a massage parlor where some workers had gone missing. After he was detained, he attempted to escape by faking a seizure but was re-arrested 12 hours later. In court, Yoo displayed erratic behavior, refusing to defend himself and lunging at judges. He attempted suicide shortly after his first court appearance.

On 13 December 2004, Yoo was sentenced to death for 20 counts of murder, although one count was later dismissed. His case brought public attention and reignited discussions about capital punishment in South Korea, especially since the death penalty had not been used since 1997. Yoo was later found to have misbehaved in prison and attempted to smuggle in adult material.

He remains detained at the Seoul Detention Center and was later transferred to a higher-security facility due to his actions in prison.