Yoo Young Chul is a serial killer who murdered 26 people during his killing spree during 2003-2004. He targeted wealthy elderly and sex workers. He is currently serving a death sentence in Seoul Prison. 

Sources:

The Raincoat Killer: Chasing a Predator in Korea (https://www.netflix.com/title/81087760) (2021), A Netflix original docuseries

Yoo Young Chul (https://web.archive.org/web/20140221072522/http://www.crimelibrary.com/serial_killers/weird/yoo_young_cheol/1.html) at crimelibrary.com Retrieved 24 December 2021

"South Korean Gov't to Introduce DNA Databank" (http://english.chosun.com/site/data/html_dir/2004/08/10/2004081061010.html) Chosun Ilbo. Arirang TV 10 August 2004 Retrieved December 24 2021

Ko, Dae-hoon; Min, Seong-jae (18 July 2004). "Suspect held in killings of masseuses, elderly". Korea JoongAng Daily. Retrieved 24 December 2021

Min, Seong-jae (20 July 2004). "Serial killer was caught by masseuses, not the police". Korea JoongAng Daily. Retrieved 24  December 2021

Im, Jang-hyuk (27 July 2004). "Police apologize for kicking woman". Korea JoongAng Daily. Retrieved 24 December  2021