so is inspector giuttari who told us carlo was in jail when he really wasn't.aking false statements in an unrelated case. and mario spezi, a high court in rome finally cleared him of criminal wrongdoing. he says the book about carlo is the last thing he'll ever write on the monster case. do you believe it? >> i believe. >> do you believe he's the one? >> i can't prove, but i believe. >> does it even matter anymore? pia was just 18 in 1984 when the monster killed her and her boyfriend. pia's mother told us she stopped wondering who the monster is long ago. knowing won't bring pia back. but doug preston says he has to know. >> why do people become obsessed? you just think you're so close, i think the next bit of information that i turn up is going to strike gold. it's going to illuminate the truth. the truth is lurking somewhere in the world, all we have to do is find it. >> the monster may never be caught, but according to one famous florentine, he'll never escape either. in his poem "the inferno," renowned italian poet dante alighieri detailed the punishments h