This Night Is Still Ours (Italian: "Questa notte è ancora nostra" ) is a 2008 Italian comedy film directed by Paolo Genovese and Luca Miniero.
The Killer Must Kill Again (Italian: L'assassino è costretto ad uccidere ancora) is a 1975 Italian giallo film directed by Luigi Cozzi.
 Cozzi originally wanted to call the film "Il Ragno" ("The Spider") but it was changed to "The Killer Must Kill Again" by the producers.
 It is based on the novel "Al mare con la ragazza" (translation: "By the Sea With the Girl") by Giorgio Scerbanenco.
 The film was also released as The Dark is Death's Friend.
 Michel Antoine (who plays the killer in this film) later played the tortured painter in Lucio Fulci's "The Beyond".
The Long Island Serial Killer (also known as The Gilgo Beach Murders) is a 2013 American true crime horror film loosely based on the elusive Long Island serial killer who murdered seventeen women on Long Island between 1996 and 2010.
Ottis Elwood Toole (March 5, 1947 – September 15, 1996) was an American drifter and serial killer who was convicted of six counts of murder.
 Like his companion Henry Lee Lucas, Toole made confessions he later recanted, but which resulted in murder convictions.
 The discrediting of the case against Lucas for crimes in which Toole had offered corroborating statements created doubts as to whether either was a genuine serial killer or, as Hugh Aynesworth suggested, both were merely compliant interviewees whom police used to clear unsolved murders from the books.
 Toole received two death sentences, but on appeal they were commuted to life imprisonment.
 He died in his cell from cirrhosis, aged 49.
 Police attributed the murder of Adam Walsh to Toole on the basis of recanted statements.
 Lucas had backed Toole's confession to the Walsh murder, claiming he had been in possession of the victim's severed head.
Albert William Goozee (1923 – 25 November 2009) was a British murderer and paedophile, whose crimes inspired the 1996 film "Intimate Relations".
 In June 1956 Goozee murdered his landlady and her teenaged daughter in the New Forest, Hampshire.
 Sentenced at the Hampshire Assizes, Winchester, to death by hanging in December 1956, Goozee was given a reprieve four days before his execution was due to take place and was instead detained at Broadmoor high-security psychiatric hospital.
 Released in 1971, Goozee, who had been diagnosed as a paranoid schizophrenic, was subsequently convicted of several further violent crimes, and in 1996 was convicted of indecently assaulting two girls, aged 12 and 13.
 Sentencing, Mr. Justice Gower said one of the two cases had been "one of the most serious cases of indecent assault that I have ever had to deal with."
 In October 2009 Goozee again became the subject of media interest when it was discovered that he had been released on compassionate grounds into the care of a nursing home for the elderly in Wigston, Leicester.
 While there, Goozee began a hunger strike and refused all food and medication.
 After developing a blood clot in his heart and complications from diabetes he died on 25 November 2009.
 The coroner recorded a verdict of death by natural causes.
 He had 5 children Christopher Goozee, Wayne Goozee, Robert Goozee, Andrea Goozee and Adrian Goozee.
 His wife Rita was unaware of the previous charges as of claires law acted in 2002.
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.
La tigre è ancora viva: Sandokan alla riscossa!
 is a 1977 Italian adventure film directed by Sergio Sollima and starring Kabir Bedi.
The Monster of Florence (Italian: Il Mostro di Firenze) is the name commonly used by the media in Italy for a series of eight double murder cases that took place between 1968 and 1985 in the province of Florence, Italy.
 Prosecution offices carried on several investigations into the cases for many years.
 The courts reached the conclusion that the murders were not committed by a single person but by a group of at least four perpetrators, who became later known as "the picknick comarades", and were definitively convicted.
 The 1968 murder was found to be a case unrelated to the others, albeit that the gun, that probably originally belonged to small local criminality, might be the same involved in the actual Monster cases.
L'assassino è ancora tra noi is a 1986 Italian horror film written and directed by Camillo Teti, and co-written by Ernesto Gastaldi and Giuliano Carnimeo.
 It is loosely based on the crimes of the Italian serial killer known as "the Monster of Florence".
The Melody of Murder, (Original Title: Mordets Melodi), is a 1944 Danish film noir directed by Bodil Ipsen and starring Gull-Maj Norin and Poul Reichhardt.
 The dark tale revolves around a sexually ambiguous serial killer whose crimes are committed to a French cabaret song, and the police suspect a chanteuse who sings the same tune during her performances.
 Produced during the German occupation of Denmark in World War II, the film was praised by critics for its "stylish cinematography, thematic intensity, and dark vision of Copenhagen;" and consider it one of the most influential Danish films of that period.

Question: How many murders cases were attributed to the serial killer on whose crimes the film L'assassino è ancora tra noi is loosely based ?
Answer: eight double murder cases