teaming up with an old italian crime reporter named mario spezi, he soon was intrigued about a serial killer italy had yet to catch. the monster of florence who killed eight couples from 1968 to 1985, then vanished. >> when you are a novelist, you are just making things up. but this was real. >> preston would quickly abandon his work of fiction for the real thing and began to learn how the monster targeted young lovers engaging in sex, mostly in cars in the hills above florence, killing first the man and then dragging the woman out of the car, mutilating and removing her genitals. for 17 years always using the same gun, the same knife, killing again and again as police failed to solve the case. >> yes, again and again the police arrested innocent people, interrogated them brutally, thought that they had extracted all kinds of really important confessions from them. >> preston says with the suspects in custody, the monster would kill again. police chased wild theories of a satanic cult. preston and spezi began to write of a lone killer and terrible police work. >> the book, you know, t

teaming up with an old italian crime reporter named mario spezi, he soon was intrigued about a serial killer italy had yet to catch. the monster of florence who killed eight couples from 1968 to 1985 then vanished. >> when you are a novelist, you are just making things up. but this was real. >> preston would quickly abandon his work of fiction for the real thing and began to learn how the monster targeted young lovers engaging in sex, mostly in cars in the hills above florence, killing first the man and then dragging the woman out of the car, mutilating and removing her genitals. for 17 years always using the same gun, the same knife, killing again and again as police failed to solve the case. >> yes, again and again the police arrested innocent people, interrogated them brutally, thought that they had extracted all kinds of really important confessions from them. >> preston says with the suspects in custody, the monster would kill again. police chased wild theories of a satanic cult. preston and spezi began to write of a lone killer and terrible police work. >> the book, you know, to

mario spezi's villa was raided, his notes confiscated and the journalist placed under arrest, though later released without charges. police surmised spezi knew so much about the killer that he just might be the killer. then preston's phone rang. >> i thought it was a joke. then they said, no, mr. preston, this is not a joke. we are coming to get you. this is obligatory. you tell us where you are. that will save everyone a lot of trouble. >> preston would find himself at the door of the prosecutor's office here in perugia where he thought he would spend a few minutes answering just a few questions. >> i had never understood how brutal, psychologically brutal an interrogation is. you feel absolutely helpless. >> and the chief interrogator was and is? >> giuliano mignini, this prosecutor who -- let me tell you something, he knows exactly what he's doing. giuliano mignini was the prosecutor for both the monster and the meredith kercher cases, just like during amanda's interrogation, preston also says he was asked to imagine scenarios of how the crime could have occurred. >> i was terrifi