ROME – Best-selling novelist Douglas Preston was researching the serial killings of lovers in Tuscany when he found himself entangled in a probe of the decades-old crime spree.

Preston had gone to Florence last month as co-author, with Italian journalist Mario Spezi, of a book about the murders and mutilation of eight couples who were parked in their cars or camped in the Tuscan countryside between 1968 and 1985.

Before returning to his home in Bristol, Maine, Preston was ordered to answer questions from a prosecutor in the murder probe. By the time the two-hour questioning was over, he said, he was under investigation for giving false statements.

“I felt like I had stumbled into one of my novels,” said Preston, whose recent thriller co-written with Lincoln Child, “Dance of Death,” features a character framed as a serial murderer. Preston, 49, has written several thrillers and horror novels, including “Relic,” co-written with Child, and “Tyrannosaur Canyon.”

During the interrogation, prosecutor Giuliano Mignini played back wiretapped conversations between Preston and Spezi, the author said.

“For some reason, he felt our conversation included code words,” Preston told The Associated Press in an interview earlier this week from his home in Maine. “At one point, we had said we would go for a walk and he demanded to know what we really meant by that.” Preston said that Spezi took him to an abandoned villa near Florence where Spezi believed a gun used to shoot the victims had been hidden.

Mignini refused to comment, citing judicial secrecy.

Michele Giuttari, who heads the police unit investigating the serial murders, said that Preston had engaged in “criminal conduct” during his stay. He contested Preston’s reconstruction of the interrogation, but declined to give details. “The only true thing is that [Preston] left the interrogation as a person under investigation” for giving false statements, Giuttari said.

In 1994, an Italian court convicted Pietro Pacciani, a farmhand dubbed “the monster of Florence” by the Italian media, of most of the slayings and sentenced him to life in prison. An appeals court acquitted him in 1996. Italian law allowed prosecutors to appeal the acquittal, and Pacciani died in 1998 while awaiting the ruling of Italy’s top criminal court. In 1998, another court convicted two other Italian men as accomplices in the slayings.

Two of the victims were French and two were German.

Some investigators suspect that those convicted were doing the bidding of a secret club that wanted body parts for satanic rituals.