Knox prosecutor tainted by 'satanism' case

One of Italy's most rambunctious legal performers, the scourge of Amanda Knox, was back in action last week.

Plump, pompous and perspiring, Giuliano Mignini, 60, may look like a character out of Dickens, but in persuading a Perugia jury to convict Knox and her Italian boyfriend Raffaele Sollecito of murdering Knox's English flatmate Meredith Kercher, the public prosecutor for the city of Perugia earned himself a reputation for steely ruthlessness in nailing his enemies.

A devout Catholic with a dim view of lax modern ways, he went on to demand that Knox serve not 26 years, as decided by the court, but life. And he was on form again this week, adding to the American student's woes by prosecuting her for slander. During the murder trial, Knox had claimed that, during an all-night grilling, a woman police officer had repeatedly slapped her. Mignini said "the good name of the Perugia police" had been attacked and asked the judge to add another six years to Knox's sentence.

But the fact that Mignini himself was only able to speak in court thanks to the indulgence of two judges in Florence went unmentioned. In January, the lawyer was convicted of abuse of office by a court in the Tuscan capital and sentenced to two years and four months in jail. The bench ruled that he and Michele Giuttari, a detective-turned-thriller writer, had used their powers to persecute people they regarded as their enemies: tapping their phones, interrogating them, putting them under investigation without any evidence against them and even getting them jailed, for personal reasons.

Giuttari enjoyed international success with his novel A Florentine Death, and the Florence prosecutors argued that he was the instigator of the crimes. Mignini, they said, was the passive partner who added the gravitas of the prosecutor's office to the detective's attempts to deal legal blows to his boss and other men of power in Florence. Accordingly they asked for a much lighter sentence for Mignini. But the court decided Mignini's role was more important than that and gave him a sentence only two months shorter than his colleague's. It also banned Mignini from public office for the same term – but it suspended both sentences, allowing him to return to his Perugia office.

Ultimately Mignini may find the Florence judge's words hard to shrug off. He and Giuttari, the court said, were guilty of "almost unheard of" criminal activity, carrying out investigations "in no way related ... to their proper competence", launching criminal cases with no evidence, ordering phone taps with "quite different ends" from those cited when the taps were authorised, taps that were made "for reasons of retaliation ... against people towards whom they had reasons for hostility".

The saga began when Giuttari, a Sicilian who had worked on anti-Mafia investigations in Calabria, arrived in Florence to work for the city police. The biggest case was a string of eight double sex murders carried out between 1968 and 1985 by the so-called "Monster of Florence". Although a man was convicted of the crimes, he was acquitted on appeal and the case remained open.

Acting on tips provided by a Roman psychic called Gabriella Carlizzi, who claimed to receive information from a dead priest, Giuttari decided the murderers were a satanic cult composed of powerful Florentines: among many other bizarre details, he believed the vaginas of female victims were used in the performance of black masses. But the story's garishness was matched only by the flimsiness of the evidence Giuttari mustered to support it.

Giuttari spent more and more time on his nebulous theories and less on his duties. His boss, police chief Giuseppe De Donno, grew irritated, not only by his subordinate's unexplained absences but also at the lack of substance to his allegations. "You've got to show me something concrete!" he bawled.

We know he used those words because Giuttari was surreptitiously recording him – as he did repeatedly over the years. In the end Giuttari got his way, and was allowed to devote all his time to the Monster investigation – in the course of which he put his former boss on the list of suspects, for having "blocked" the investigation. Others accused included the city's attorney general, its top prosecutor, and the chief crime reporter of Florence's daily newspaper.

Giuliano Mignini, the court decided, "participated fully" in Giuttari's criminal conduct. Another court in the city reinforced those verdicts when it decided there was no merit to Giuttari and Mignini's "Monster" accusations and threw the entire case out.

If those two Florence verdicts cause Mignini sleepless nights, he can console himself that the Kercher case was a resounding personal success. But with the appeal of Knox and Sollecito months away, it may not be immune from the Florence contagion. Gabriella Carlizzi, the Roman mystic whose theories underlay the doomed Monster investigation, was also an influence in the prosecution of Knox and Sollecito.

On 5 November 2007, four days after Meredith's murder, she blogged that the murder "in my view is the Monster story continued with another subject". The following day Knox and Sollecito were arrested. During crucial early hearings, Mignini followed Carlizzi's intuitions, describing the murder as "a premeditated ... sexual and sacrificial rite" timed for Halloween. And, as with the Monster case in Florence, no evidence was presented to back the theory. This was what disturbed the Florence judges the most. "Mignini," they wrote, "constantly demonstrates ... an absence of sufficient thought ... an obliteration of the distinction between what is mere suspicion and what has the significance of a more pregnant accusation."

"No one," they write, "has an absolute right not to be put under investigation, even if they are innocent; but everyone has the right not to be investigated if no evidence emerges ... that goes beyond mere suspicion."

Those are words that may come back to haunt him.

* Update, February 2011: Mr Mignini has pointed out that he has appealed against the verdict and sentence referred to in this article, and the appeal is due to be heard in November 2011. At the trial mentioned above, he and Mr Giuttari were also acquitted of certain unrelated charges of abuse of office.