Question: Badlands was about a teenage serial killer who murdered how many people?

Context paragraphs:
Hunter (2015 film): Hunter is a 2015 film directed by Gregory Hatanaka and starring Ron Becks with Magda Marcella, Kristine DeBell, George Lazenby and Laurene Landon.  It follows the exploits of a veteran cop who must hunt down a cop killer as well as a female teenage serial killer.

Cold Fish: Cold Fish (冷たい熱帯魚 , Tsumetai Nettaigyo ) is a 2010 Japanese horror-drama serial killer film directed by Sion Sono.  The film is about a quiet and unambitious owner of a tropical fish shop whose life and family are taken over by a fellow fish entrepreneur who happens to be a serial killer.  The film is loosely based on the exploits of two Tokyo serial killers, Sekine Gen and Hiroko Kazama, a husband and wife duo who owned a pet shop and murdered at least four people.

Charles Starkweather: Charles Raymond "Charlie" Starkweather (November 24, 1938 – June 25, 1959) was an American teenaged spree killer who murdered eleven people in the states of Nebraska and Wyoming in a two-month murder spree between December 1957 and January 1958.  All but one of Starkweather's victims were killed between January 21 and January 29, 1958, the date of his arrest.  During the murders committed in 1958, Starkweather was accompanied by his 14-year-old girlfriend, Caril Ann Fugate.

Long Island serial killer: Long Island serial killer (also referred to by media sources as the Gilgo Beach Killer or the Craigslist Ripper) is an unidentified suspected serial killer who is believed to have murdered 10 to 16 people associated with prostitution, over a period of nearly 20 years, and dumped their bodies along the Ocean Parkway, near the remote Long Island, New York beach towns of Gilgo Beach and Oak Beach in Suffolk County, and the area of Jones Beach State Park in Nassau County.

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.

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.

I Was a Teenage Serial Killer: I Was a Teenage Serial Killer is an underground no budget film written and directed by "The Queen of Underground Film", Sarah Jacobson.  It is a short black-and-white film of a 19-year-old girl who is sick of sexist men and kills them.  It was Jacobson's first film and it was released through her own company, Station Wagon Productions.  She made the film under the guidance of her teacher, George Kuchar.  The film featured songs by Heavens to Betsy.

Gary Ridgway: Gary Leon Ridgway (born February 18, 1949) is an American serial killer known as the Green River Killer.  He was initially convicted of 48 separate murders and is presumed to be responsible for more than 90.  As part of his plea bargain, an additional conviction was added, bringing the total number of convictions to 49, making him the most prolific American serial killer in history according to confirmed murders.  He murdered numerous women and girls in Washington State during the 1980s and 1990s.

Bible John: Bible John is the nickname of a serial killer who is believed to have murdered three young women after meeting them at the Barrowland Ballroom in Glasgow, Scotland, between 1968 and 1969.  The killer has never been identified although the known movements and modus operandi of convicted Glaswegian serial killer Peter Tobin suggests that he may have been behind the killings.  However, this has never been proven and the case remains unsolved.

Badlands (film): Badlands is a 1973 American crime film written and directed by Terrence Malick, starring Martin Sheen and Sissy Spacek, and featuring Warren Oates and Ramon Bieri.  The story, though fictional, is loosely based on the real-life murder spree of Charles Starkweather and his girlfriend, Caril Ann Fugate, in 1958, though that basis was not acknowledged when the film was released.

Supporting paragraphs: Badlands (film) Charles Starkweather
Answer: eleven