Question: How many people was this American contract killer and serial killer, who was the subject of the movie The Iceman, convicted of killing?

full_context: Document 1: The Frozen Ground: The Frozen Ground is a 2013 American crime thriller drama film directed and written by Scott Walker in his directorial debut, and starring Nicolas Cage, John Cusack, Vanessa Hudgens, Katherine LaNasa, Radha Mitchell and 50 Cent. Based on the crimes of real-life Alaskan serial killer Robert Hansen, the film depicts an Alaskan State Trooper seeking to apprehend Hansen by partnering with a young woman, who escaped from Hansen's clutches.
Document 2: The Irishman (2019 film): The Irishman is an upcoming American biographical crime film directed by Martin Scorsese and written by Steven Zaillian, based on the book "I Heard You Paint Houses: Frank ‘The Irishman’ Sheeran and the Inside Story of the Mafia, the Teamsters, and the Final Ride by Jimmy Hoffa" by Charles Brandt. The film stars Robert De Niro, Al Pacino, Joe Pesci, Bobby Cannavale, Harvey Keitel, and Ray Romano. The film is tentatively set for release in 2019 by Netflix.
Document 3: Dennis Rader: Dennis Lynn Rader (born March 9, 1945) is an American serial killer who murdered ten people in Sedgwick County, Kansas between 1974 and 1991.
Document 4: Murder, Inc.: Murder, Inc. (or Murder Incorporated) was the name the news media gave to organized crime groups in the 1930s and 40s that acted as the enforcement arm of the Italian-American Mafia, Jewish mob, and connected organized crime groups in New York and elsewhere. The groups were largely composed of Italian-American and Jewish gangsters from the Brooklyn neighborhoods of Brownsville, East New York, and Ocean Hill. Originally headed by Louis "Lepke" Buchalter, and later by Albert "The Mad Hatter" Anastasia, Murder, Inc. was believed to be responsible for between 400 and 1,000 contract killings, until the group was exposed in the early 1940s by former group member Abe "Kid Twist" Reles. In the trials that followed, many members were convicted and executed, and Abe Reles himself died after "falling out of a window". Thomas E. Dewey first came to prominence as a prosecutor of Murder, Inc. and other organized crime cases.
Document 5: The Iceman (film): The Iceman is an American biography crime thriller film based on the true story of longtime notorious hitman Richard Kuklinski. Released in 2012 at the Venice Film Festival, the film was directed by Ariel Vromen, and stars Michael Shannon as Kuklinski, Winona Ryder, Chris Evans, and Ray Liotta.
Document 6: Criminal (2016 film): Criminal is a 2016 American action crime thriller drama film directed by Ariel Vromen and written by Douglas Cook and David Weisberg. The film is about a convict who is implanted with a dead CIA agent's memories to finish an assignment. The film stars Kevin Costner, Gary Oldman, and Tommy Lee Jones, in the second collaboration between all three following the 1991 film "JFK". The film also features Alice Eve, Gal Gadot, Michael Pitt, Jordi Mollà, Antje Traue, Scott Adkins, Amaury Nolasco, and Ryan Reynolds.
Document 7: Contraband (2012 film): Contraband is a 2012 American crime thriller film directed by Baltasar Kormákur, starring Mark Wahlberg, Kate Beckinsale, Ben Foster, Caleb Landry Jones, Giovanni Ribisi, Lukas Haas, Diego Luna and J. K. Simmons. The film is a remake of the 2008 Icelandic film "Reykjavík-Rotterdam" which Baltasar Kormákur starred in. It was released on January 13, 2012 in the United States by Universal Pictures.
Document 8: Contract killing: Contract killing is a form of murder in which one party hires another party to kill a target individual or group of people. It involves an illegal agreement between two or more parties in which one party agrees to kill the target in exchange for some form of payment, monetary or otherwise. Either party may be a person, group, or an organization. In the United States, the crime is punishable by 15 years to life in a state penitentiary. Contract killing has been associated with organized crime, government conspiracies and with vendettas. For example, in the United States, the gang Murder, Inc. committed hundreds of murders on behalf of the National Crime Syndicate during the 1930s and 1940s.
Document 9: 12 (2007 film): 12 is a 2007 crime film by Russian director and actor Nikita Mikhalkov. Mikhalkov was awarded the Special Lion at the 64th Venice International Film Festival for his work on the film, which also received an Academy Award nomination for Best Foreign Language Film. It is an adaptation of Reginald Rose's play "Twelve Angry Men" and a remake of Sidney Lumet's film "12 Angry Men".
Document 10: Richard Kuklinski: Richard Leonard Kuklinski (April 11, 1935 – March 5, 2006) was an American contract killer and serial killer who was convicted of murdering five people, though he likely killed at least several dozen more. He was associated with members of the American Mafia, namely the DeCavalcante crime family of Newark, New Jersey, and the Five Families of New York City.
Document 11: David Berkowitz: David Richard Berkowitz (born Richard David Falco; June 1, 1953), known also as the Son of Sam and the .44 Caliber Killer, is an American serial killer who pled guilty to eight separate shooting attacks that began in New York City during the summer of 1976. The crimes were perpetrated with a .44 caliber Bulldog revolver. He killed six people and wounded seven others by July 1977. As the number of victims increased, Berkowitz eluded the biggest police manhunt in the history of New York City while leaving letters that mocked the police and promised further crimes, which were highly publicized by the press. The killing spree terrorized New Yorkers and achieved worldwide notoriety.
Document 12: John Wick: John Wick is a 2014 American neo-noir action thriller film directed by Chad Stahelski and David Leitch. It stars Keanu Reeves, Michael Nyqvist, Alfie Allen, Adrianne Palicki, Bridget Moynahan, Dean Winters, Ian McShane, John Leguizamo and Willem Dafoe. The first installment in the "John Wick" film series, the story focuses on John Wick (Reeves), a retired hitman seeking vengeance for the theft of his vintage car and the killing of his puppy, a gift from his recently deceased wife. Stahelski and Leitch directed the film together, though Leitch was uncredited.
Document 13: Iceman (2014 film): Iceman, formerly known as The Iceman Cometh, is a 2014 Hong Kong-Chinese 3D martial arts action-comedy film directed by Law Wing-cheung and starring Donnie Yen, who also serves as the film's action director. The film is a remake of the 1989 film "The Iceman Cometh" which was directed by Clarence Fok and starred Yuen Biao, who was earlier reported to join the film. Donnie Yen hand-picked Jam Hsiao for his unique voice and deep emotions to sing the Mandarin theme song. The Cantonese version is sung by Hong Kong singer and actor Julian Cheung. The film was released in Hong Kong and China on April 25, 2014.
Document 14: Anthony Casso: Anthony Salvatore "Gaspipe" Casso (born May 21, 1940 in Brooklyn, New York City) is an Italian-American mobster and former underboss of the Lucchese crime family. During his career in organized crime, Casso was regarded as a "homicidal maniac" in the American Mafia, single-handedly killing over 40 to 50 people, and ordering as many as 100 or more murders. Former Lucchese captain and government witness Anthony Accetturo once said of Casso, "all he wanted to do is kill, kill, get what you can, even if you didn't earn it." In interviews and on the witness stand, Casso has confessed involvement in the murders of Frank DeCicco, Roy DeMeo, and Vladimir Reznikov. Casso has also admitted to several attempts to murder Gambino family boss John Gotti.
Document 15: 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.
ground_truth: five