Christopher McQuarrie and Nathan Alexander, who wrote the screenplay for the 2008 World War II thriller Valkyrie about a plot to assassinate Hitler, will write the screenplay for the film.
The 'Monster of Florence' was said to locate couples in secluded spots and murder them, often with a .22 Beretta gun. The killer or killers would sometimes cut out the woman's pubic area with a knife in what was one of the biggest riddles in modern Italian criminal history.
Some have claimed the murders were committed by members of a satanic sect or on their behalf. The killings terrorised many Italians at the time and made them fearful of parking their vehicles, walking or camping in the countryside.
A local farmer, Pietro Pacciani, was convicted of the murders, but was later acquitted. Pacciani died in 1998, before his case could be heard by the Italian supreme court for a final verdict.
Antonio Vinci, the son of Sardinian criminals, was more likely to have been the serial killer than Pacciani, according to Preston's book The Monster of Florence, which he wrote with Italian crime reporter Mario Spezi.
Vinci recently denied the accusation in an interview on American TV. Preston and Spezi were briefly jailed for obstructing justice.
The Monster of Florence serial killings inspired a character in Thomas Harris's novel Hannibal, although the subplot was dropped from the final version of the film and can only be seen on DVD.
The movie will be the second made by Clooney in the past two years, after The American, in which he played an assassin lying low in the Italian countryside and includes steamy sex scenes.
The film will allow Clooney to spend more time in Italy, where he has an Italian girlfriend, the showgirl Elisabetta Canalis, and a villa on Italy's picturesque northern Lake Como.
US star Tom Cruise was previously attached to the film after securing the screen rights in August 2008, not long after Preston and Spezi's book was published.