Daniele La Monaca/Reuters

For five months now in the Umbrian hill town of Perugia, an American exchange student called “Angel Face” by the tabloid press has been on trial for the murder of her roommate. On Friday, for the first time, that student, Amanda Knox will testify on her own behalf.

The case against Knox has so many holes in it, and is so tied to the career of a powerful Italian prosecutor who is under indictment for professional misconduct, that any fair-minded jury would have thrown it out months ago.

That is not to say the Italian courts are not fair-minded. We kill innocent Americans often enough through our legal system, kill them because of shoddy police work or racial prejudice. Knox’s fate is in the hand of six jurors, two judges among them, who meet two days a week and will soon take a long summer break before reaching a verdict in the fall.

But this is not about whose system is better. This is about a high-spirited British student, Meredith Kercher, found strangled and stabbed in November of 2007 in the Perugian cottage she shared with Amanda Knox. Justice must be done. And in fact, a man has already been convicted of her murder – more about that in a moment.

But it is also about Amanda Knox, an equally high-spirited student whose life has been nearly ruined by this collision of predatory journalism and slipshod prosecution – “the railroad job from hell,” as one outside expert hired by CBS News concluded.

Amanda Knox was 20 years old, a Jesuit-educated student from a Seattle family without money, when she arrived in Italy for a term abroad. She had worked three jobs while attending the University of Washington to save money for this trip. She had no criminal record, was an athlete whose soccer tricks had earned her a grade school nickname of “Foxy Knoxy,” a lover of theater and the written word. And she was also a “little spacey,” in the words oft-used by friends to describe her.

She started seeing an Italian student, Raffaele Sollecito, the son of a prominent doctor. They spent the night of the murder at his apartment, she said, and no reliable witness or credible evidence has ever placed them at the crime scene. But within days of the killing, these two would be painted across Europe as thrill-seekers who killed a woman in a drug-fueled orgy.

That may sound like a preposterous motive for a murder by college kids, but it’s a recurring obsession for the prosecutor in the Knox case.

“Case closed,” the Italian authorities said in those first days of November, 2007, even though they had yet to arrest the only man who has ever been found guilty of the murder.

As it happened, my daughter was studying in Italy at the same time – like Knox, una studentessa di Seattle. They did not know each other. But after the tabloid fallout, any female exchange student from Seattle was suddenly cast in a dark light.

After my daughter wrote about her experience for this newspaper, she found the paparazzi camped outside her room in Bologna. For all of that, our family consider ourselves honorary Italians; we lived there for a short while, our kids went to grade school there, and we love the country dearly.

Knox may not feel the same way. She spent nearly a year in jail without being charged. This, despite the fact that the only physical evidence found on the murder victim’s body was from someone else – a drifter with a drug problem named Rudy Guede.

Shortly after the crime, Guede fled Italy for Germany. His prints and his DNA were found in Kercher’s room and on the body. After being arrested, he underwent a fast-track trial and was found guilty last fall of complicity in the murder, and sentenced to 30 years in prison.

That should have been the end of it. Guede initially told one story: that he had sex with Kercher and then went into the bathroom, plugged in his iPod, and came out to find a strange man standing over her with a knife.

Then, months later, Guede changed his story: he said that strange man was now Sollecito, assisted by Amanda Knox in a sex game that went wrong. Neither of them had been named by him before. Guede denied being the killer.

But if Knox and Sollecito had killed Kercher, and were in that blood-splattered room, why is there no physical trace from them on the body? A print? A swap of DNA somewhere? After all, Kercher had died after a brutal strangulation, evidence of considerable struggle, with knife pokes in the neck.

“In every murder, the killer always leaves something behind and always takes something with him,” said Anne Bremner, a former prosecutor and prominent attorney, a member of International Academy of Trial Lawyers, who is assisting the Knox family, pro-bono – though she has no role in the actual defense. “All the forensic evidence points to Rudy Guede.”

The prosecution says at least one of the college students did leave something behind. They said they found a bra clasp with Sollecito’s DNA on it. But they discovered Kercher’s clasp nearly six weeks after the murder – a highly suspect and tainted piece of evidence from a contaminated crime scene.

Knox and Sollecito were arrested in large part because of what they said under duress by interrogation of the prosecutor, Giuliano Mignini. Remember that name. After being questioned all night without an attorney or a professional translator, Knox said some things in response to a series of hypothetical questions. This was initially trumpeted as a contradiction, or worst – a confession. A higher court later threw out the most damning statements.

Lurid details were leaked to a press corps that trolled through Knox’s college sex life – something they would never do to a man. Her social network computer pictures, showing the usual 20-year-old drinking faces, were splashed across front pages.

The Brits, in particular, had a field day. Locked from her house in the first days after it became a crime scene, Knox went to a store one day with Sollecito to buy emergency underwear. The British tabs bannered this as a g-string celebration of remorseless killers.

Little wonder that an Italian television poll found Amanda Knox a bigger personality than Carla Bruni.

Still, Knox’s statements were troubling. She and Sollecito gave different versions of what they had done the night of the killing, their memories clouded no doubt because they’d been smoking hashish. And Knox raised the possibility that a bar owner with an airtight alibi could have been involved.

The authorities later claimed they found the murder weapon, a kitchen knife, at Sollecito’s house. The knife had Knox’s DNA on the handle – no surprise, considering how much time she spent with her boyfriend. But it was also described, after repeated and highly questionable testing, as containing a tiny amount of DNA that might match that of the victim.

That DNA, according to several outside experts, was of such trace amounts, and was available only after numerous enhancements in the testing, that it could belong to many people. Also, the knife did not match the bloody outline of a knife at the crime scene.

So why push forward against Knox and Sollecito? They had no motive. The evidence is flawed and flimsy.

One explanation comes from Douglas Preston, a prominent best-selling American author who lived in the Florentine hills while researching a book about a serial killer never found, “The Monster of Florence,” co-authored by Italian journalist Mario Spezi.

After the serial murders stopped, a prosecutor decided to reopen the case. His theory was that the killer or killers were Satanists from an ancient cult that harvested body parts. That prosecutor is the same one in the Knox case – Giuliano Mignini.

“One day I’m walking down the streets of Florence when my cell phone rings,” said Preston in an interview. “They say, ‘This is the police – we’re coming to get you.’” For three hours, the author was interrogated by Mignini about possible connections to the case. His phone calls with co-author Spezi had been wiretapped, and Mignini asked him to explain things. Preston said he was told he must confess to perjury or obstruction of justice.

“I’m not the kind of person who could be broken down,” said Preston. “But now I’m terrified. My wife and kids are out having lunch, and I’m thinking I’m never going to see them again.”

Preston is indicted – Mignini has that power – but then told he can go free if he leaves Italy. The author departs the next day, banished, humiliated and deeply troubled.

Fast forward to the Amanda Knox interrogations. She’s 20, hardly a world sophisticate, who spoke only passable Italian at the time. Mignini used the same methods – a pattern now coming to light in the misconduct case against him, in which he is accused by a Florentine judge of intimidation and wiretapping journalists and other perceived enemies. He has denied any misconduct. When Preston looked at the case against Amanda Knox, he saw a rogue prosecutor and a miscarriage of justice.

“There was no evidence,” he said. “I realized it was all bogus. Mignini believes that Satan walks the land and anyone who is against him must be working for the other side.”

One more thing about this case: a civil suit by the victim’s family and the wrongly accused bar owner is going forth at the same time, meaning that highly prejudicial information that a criminal jury would not usually hear is being aired, before the same people.

Amanda Knox faces 30 years in prison if convicted. For Mignini, what is at stake is his reputation, his honor – no small things in Italy. I’m haunted by an observation from Rachel Donadio, my Times colleague in Rome. In last Sunday’s paper, in trying to explain Silvio Berlusconi, she wrote:

“In Italy, the general assumption is that someone is guilty until proven innocent. Trials – in the press and in the courts – are more often about defending personal honor than establishing facts, which are easily manipulated.”

All trials are about narrative. In Seattle, where I live, I see a familiar kind of Northwestern girl in Amanda Knox, and all the stretching, the funny faces, the neo-hippie touches are benign. In Italy, they see a devil, someone without remorse, inappropriate in her reactions.

In the end, of course, this is about the victim. Meredith Kercher is gone, a daughter no more, leaving behind the “brutality, the violence, and the great sorrow it has caused,” as her mother said in court last week.

But one life taken should not keep anyone from asking the right questions before ruining two others.