Tomorrow morning is judgment day in the four-year saga of Amanda Knox, the American convicted of murdering her roommate in what Italian police and prosecutors have called a “sex game gone wrong.”

Meredith Kercher was killed in Perugia the night after Halloween 2007; Knox and her boyfriend, Raffaele Sollecito, were the first people on the scene when police arrived. Four days later, they were arrested, and two years later, convicted, along with a third man, local resident Rudy Guede.

The story of Amanda Knox in Italy is of media, misogyny, mistranslation, misbehavior — but chiefly superstition. Kercher’s death was a terrible but simple act of sexual aggression against a young woman in her home. Yet while a prosecutor in the United States might see only the forensic evidence, the motives and the opportunity — the small-town Italian prosecutor Giuliano Mignini saw something more. It was a Halloween crime, and that was one of the first clues to register with Mignini, called to the crime scene fresh from celebrating All Souls’ Day, a day when proper Italian families visit their dead.

And on scene was a pale, light-eyed 20-year-old girl who, prosecutors said in their closing arguments last week, had the look of a “she-devil.”

Mignini always included witch fear in his murder theory, and only reluctantly relinquished it. As late as October 2008, a year after the murder, he told a court that the murder “was premeditated and was in addition a ‘rite’ celebrated on the occasion of the night of Halloween. A sexual and sacrificial rite [that] in the intention of the organizers … should have occurred 24 hours earlier” — on Halloween itself — “but on account of a dinner at the house of horrors, organized by Meredith and Amanda’s Italian flatmates, it was postponed for one day.”

Eventually, Mignini’s No. 2, the chain-smoking, no-nonsense Manuela Comodi, persuaded him to drop the references to Satanism. But no one forgot about it, not the jury, not the judge, not the press, not the Perugians, not the court spectators, who could never look at Amanda without wondering whether a whiff of sulfur surrounded her.

Un festino di giochi proibiti — literally, “a party of forbidden games.” The phrase first appeared in the Giornale dell’Umbria the day after the arrests and was quickly picked up worldwide. This was later simplified to gioco erotico — “erotic game.”

The police and prosecutor would have to wait weeks for the DNA evidence. While they waited, they had much circumstantial evidence — including the strange delay in calling the police on the morning after Amanda saw blood and they found the broken window.

They also had what they could see with their naked eyes. What they saw was a dead girl in a bloody room in a house that had been unlocked and seemed to have been wiped clean. There didn’t seem to have been a fight anywhere but in the murder room. A large bottle of water stood open on the kitchen table, a few cigarettes were in ashtrays, a chair was knocked over in the dining area, but otherwise the place was spick-and-span.

The Perugia police didn’t have the CSI expertise to deal with what was clearly going to be a high-profile case. While they were waiting for the scientific analyses from Rome, this is what the public minister and his investigators had from the house:

Kercher was killed by a cut to the neck on a Thursday night, in her own bedroom.

There were five left Nike shoe prints in blood on the pillowcase that had been shoved under Kercher’s hips.

There were three more bloody left shoe prints on the tile floor around the body, matching those on the pillowcase.

The shoe prints looked very much alike.

There was one bloody bare right footprint on the fuzzy blue bath mat in the smaller bathroom. It was from a large foot and therefore presumably male.

One broken window.

There was a small but visible dried smear of blood on the bathroom faucet.

There were unflushed feces in the toilet in the larger bathroom.

There was blood on a wall in the downstairs apartment, determined to be that of a black cat.

The police dusted the house for fingerprints. Dozens turned up, too many to categorize. Police paid attention only to the ones for which they had matches — the five girls, including Amanda and Meredith, who lived in the house, and the four Italian boys who lived downstairs and were out of town the night of the murders. The only identifiable prints in Meredith’s room were Guede’s, although 14 were unmatchable. Police found Amanda’s prints in one place only, on a water glass in the kitchen.

There was no visible blood or strands of hair or threads of torn cloth on the broken glass bits still on the windowsill, and no fingerprints on Meredith’s locked doorknob, although there was a smear of her blood on the latch.

To the superstitious-minded, it might seem that whoever had come in through that window — if anyone had — possessed superhuman powers of levitation and an uncanny lightness of touch that had left not a single trace on the narrow, jagged entrance.

To understand Mignini’s worldview, to get what he saw when he looked at the crime scene at Hallowtide, on a Thursday night, and to see what led him to think of a woman leading a sex game, we must dig far back into the history of the long battle of Catholicism versus alternative spirituality in Italy and know its signs and symbols as well as he does.

There are many rooms in the mansion of Mignini’s rich cultural heritage, as there are in Italy’s culture in general. Some of them, like the Uffizi Gallery, are open to tourists, some are to be found in books by Boccaccio or Petrarch, in the poetry of Dante. Others — Catholicism and the Vatican — can be glimpsed through stained glass but never fully seen. And then there are other rooms — darker, utterly closed and locked against the prying eyes of outsiders, rooms with keys that perhaps only native Italians hold.

In interviews, Mignini made no secret of his belief in the prevalence and possibility of conspiracy — both in the world at large and against him personally. He found the American tendency to ridicule or officially rule out conspiracy naive in the extreme.

“Why do they call it a conspiracy theory?” he asked. “What does ‘conspiracy theory’ mean? How can you call a conspiracy theory the fact that more than one person did a crime together? Why are they called conspiracy theories? Caesar was killed by 20 senators. Is that a conspiracy theory? It’s normal that people work together. I remember Ruby and Oswald together. Ruby killed Oswald to shut him up. I could see that on TV. Why did he kill him? He was afraid he was going to talk.”

Mignini got encouragement and theoretical assistance in the esoteric aspects of previous investigations from an unusual source: Gabriella Carlizzi, a wealthy Roman woman and courthouse gadfly whose day job consisted of running a Catholic charity that worked with prisoners. Carlizzi, who died of cancer in 2010, was, like Mignini, a serious practicing Catholic herself who had dedicated her life to exposing and fighting satanic sects.

Before her death, Carlizzi operated out of a home office in a spacious apartment on one of the most ancient roads out of Rome, replete with white grand piano, bronze statuary and fluffy lap dog. She made herself up in what Americans might recognize as high Staten Island style, with designer eyeglasses, lip liner and ample tanned cleavage on display. Childhood polio had left her with a limp and a dedication to art, literature and a form of Christian spirituality that recognizes agents of Satan in an astonishing array of modern-day organizations and societies.

One of Carlizzi’s primary obsessions were the Masons.

There are 24 Masonic lodges in Perugia, making it Italy’s per-capita center of Masonic activity. Perugians believe that members of those lodges secretly control most aspects of banking, business and administration in their community.

Mignini grew up around their symbols, and because church and Italian history fascinated him, he knew them better than most.

Masonic initiation rites are rooted in a hodgepodge of alchemy and ancient religious practices and texts, from the Mithraic mysteries to the Egyptian Book of the Dead and the Bible itself. Members can attain several “degrees,” and at each degree, a separate initiation rite takes place. Initiates are blindfolded and asked to leave their worldly belongings at the door.

They either untie their shoes or actually remove one shoe, which seems to be a nod to a piece of pagan symbolism of stepping into and out of the underworld.

Mignini was very familiar with this Masonic ritual. At 7 via della Pergola, the home of Meredith and Amanda, the track of single bloody shoe prints was evidence enough of their involvement.

Mignini was also comfortable with the notion that his Catholic Church still battles the forces of paganism, and chief among the church’s traditional pagan foes was an old cult in Italy that revered the fertility goddess Diana. Italian women executed as witches in the 1300s said they followed a “lady of the game” into the forest, where they practiced animal transformation, becoming beasts that could fly, and traveled long distances, entering houses through windows and walls, drinking wine, leaving behind feces, and waking up in their own beds the next morning unsure of how they’d gotten home.

The practitioners called those gatherings “games.” For some unclear reason, the game nights traditionally fell on Thursdays.

DNA evidence would eventually prove that Guede sexually assaulted Kercher, and he was convicted of her killing.

But Mignini would not believe such a simple explanation. The date, the shoe prints, the parallels to pagan rituals — this was an occult death ceremony, and Knox was at the center of it.

If the lack of physical evidence exonerates Knox in Italian court tomorrow, Mignini will be unbowed — he will likely believe the Masons have once again won.

Reprinted with permissions from “The Fatal Gift of Beauty” by Nina Burleigh. Copyright (c) 2011 by Nina Burleigh. Published by Broadway Books, an imprint of the Crown Publishing Group, a division of Random House, Inc.