Question: The serial killer who inspired "The Chaser" admitted to murdering how many people?

Context paragraphs:
Satish (criminal): Satish (born c. 1973) is a convicted Indian pedophile and serial killer who was active in Bahadurgarh in Haryana from 1995 to 1998.  He admitted kidnapping and attempting to rape fourteen girls, murdering ten.  Police confirmed Satish's involvement in twelve cases, including the ten murders.  Since his victims were all five to nine years of age, he is also known as the Bahadurgarh baby killer.

Yoo Young-chul: Yoo Young-chul (born April 18, 1970) is a South Korean serial killer and self-confessed cannibal.  Although he admitted to murdering 21 people, mostly prostitutes and wealthy old men, the Seoul Central District Court convicted him of 20 murders (one case was dismissed on a technicality).  Yoo burned three and mutilated at least 11 of his victims, admitting he ate the livers of some of them.  He committed his crimes between September 2003 and July 2004, when he was arrested.  Yoo explained his motives in front of a TV camera saying "Women shouldn't be sluts, and the rich should know what they've done."

List of serial killers by number of victims: A serial killer is a person who murders three or more people, in two or more separate events over a period of time, for primarily psychological reasons.  There are gaps of time between the killings, which may range from a few hours to many years.  This list shows serial killers from the 20th century to present day by number of victims.  In many cases, the exact number of victims assigned to a serial killer is not known, and even if that person is convicted of a few, there can be the possibility that he/she killed many more.

The Chaser (film): The Chaser () is a 2008 South Korean action thriller film starring Kim Yoon-seok and Ha Jung-woo.  It was directed by Na Hong-jin in his directorial debut.  Inspired by real-life Korean serial killer Yoo Young-chul, the film was shot on location around Mangwon-dong in the Mapo District, Seoul.

My Brother the Serial Killer: My Brother the Serial Killer is a 2012 American television documentary about serial killer Glen Rogers, otherwise known as the "Casanova Killer", who was convicted for a series of murders and arsons.  The documentary was narrated by Rogers' brother Clay Rogers and aired on Investigation Discovery in November 2012.  "My Brother the Serial Killer" received widespread media attention for Clay's claims that his brother was responsible for the 1994 murders of Nicole Brown Simpson and Ronald Lyle Goldman.

Luis Garavito: Luis Alfredo Garavito Cubillos, also known as "La Bestia" ("The Beast") or "Tribilín" (named after Disney character "Goofy"'s Latin American Spanish name) is a Colombian rapist and serial killer.  In 1999, he admitted to the rape, torture and murder of 147 young boys.  His victims, based on the locations of skeletons listed on maps that Garavito drew in prison, could eventually exceed 300; Garavito continues to confess to more murders.  He has been described by local media as "the world's worst serial killer".  According to the Attorney General's Office and various judicial bodies, Luis Alfredo Garavito is the "second serial killer of the world."  Likewise, the judicial body ruled that all Garavito's sentences total 1853 years and nine days in jail.

Charles Cullen: Charles Edmund Cullen (born February 22, 1960) is a former nurse who is the most prolific serial killer in New Jersey history and is suspected to be the most prolific serial killer in American history.  He confessed to authorities that he killed up to 40 patients during the course of his 16-year nursing career.  But in subsequent interviews with police, psychiatric professionals, and journalists Charles Graeber and Steve Kroft, it became clear that he had killed many more, whom he could not specifically remember by name, though he could often remember details of their case.  Experts have estimated that Charles Cullen may ultimately be responsible for 400 deaths, which would make him the most prolific serial killer in American history.

Juan Díaz de Garayo: Juan Díaz de Garayo y Ruiz de Argandoña, also known as "The Sacamantecas" ("The fat extractor" in Spanish) (October 17, 1821 – May 11, 1881), was a Spanish serial killer active near Vitoria, Álava, who strangled five women and a 13-year-old girl, and attacked four other women during two different periods, 1870 to 1874 and 1878 to 1879.  A lust-motivated serial killer, Garayo first killed prostitutes after hiring and sleeping with them consensually, but grew more disorganized and violent as time went on, attacking, raping and murdering women that he saw walking alone in the country.  His last two victims, murdered in consecutive days, were also stabbed, and the second was disembowelled.

Cold North Killers: Canadian Serial Murder: Cold North Killers: Canadian Serial Murder is a 2012 Canadian non-fiction book written by Lee Mellor and published by Dundurn Press.  It documents the lives of sixty Canadian serial killers, with the earliest being Edward H. Rulloff and the most recent being Russell Williams.  The book uses Katherine Ramsland's interpretation of what constitutes a serial killer—someone who has killed at least two people on two separate occasions, and who attempted to or likely would have killed again—as outlined in her 2007 book "The Human Predator".  "Cold North Killer's" own definition of what constitutes a Canadian serial killer includes both Canadians who committed murder abroad (such as Keith Hunter Jesperson and Gordon Stewart Northcott) and non-Canadians who committed murder in Canada (like William Dean Christenson and Earle Nelson).

Red Dragon (novel): Red Dragon is a novel by American author Thomas Harris, first published in 1981.  The plot follows FBI profiler Will Graham, who comes out of retirement to investigate a serial killer nicknamed The Tooth Fairy, who is murdering entire families.  The novel introduced the character Dr. Hannibal Lecter, a brilliant psychiatrist and cannibalistic serial killer to whom Graham turns for advice.

Supporting paragraphs: The Chaser (film) Yoo Young-chul
Answer: 21