It all began about two years ago when a shopkeeper and an insurance agent from the small town of Sant'Arcangelo, east of Naples, told their story to a local radio disc jockey.
Aware of DJ Filippo D'Agostino's anti-usury crusade, Mr Leonardo Tatalo and Mr Antonio Stipo went to him with the story of their experiences at the local branch of the Banco Di Napoli in Sant'Arcangelo.
Both men claimed the branch manager, Mr Filippo Lemma, had formed a "bank within the bank", comprising about 50 of the bank's most indebted clients. All the debtors had been "invited" to sign a series of blank cheques and cambiali (a type of draft bank bill) which, it was alleged, would help get them out of debt.
The debt of Mr Tatalo, the shop owner, to the bank grew from £26,000 to £140,000 in the space of a year, as he found himself caught up in a usury ring which charged interest rates of 400 per cent. Mr Stipo's experience was similar. In frustration and despair, both men turned to Mr D'Agostino, who accompanied them first to a local police station and then to Finance Police Headquarters in Rome.
Ironically, the formal complaint registered in Rome was to lead to the most outspoken critic of the practice of usury in all of southern Italy, Cardinal Michele Giordano of Naples. For it was the contention of Mr Tatalo and Mr Stipo, subsequently upheld by investigating magistrates, that the Sant'Arcangelo loan-sharking racket had been masterminded by Mr Mario Lucio Giordano, brother of the cardinal and business associate of Mr Lemme.
Both Mr Giordano and Mr Lemme were arrested last week on charges of criminal association, usury and extortion. For Cardinal Giordano, the arrest of his brother was both distressing and embarrassing - but worse was to come.
Last Saturday morning, 30 Finance Police officers, led by state prosecutor Mr Michelangelo Russo, staged a raid on his Curia offices in Naples. The state investigator served formal notice on the 67-year-old cardinal that he was under investigation on the same charges as his brother. He furthermore requested that his officers be allowed to take away documentation and computer disks.
In the avviso di garanzia, the formal judicial notice served on the cardinal, it is stated that he is under investigation because of the transfer of substantial sums of money to a current account, held in his name but overseen by his brother.
In layman's language, the investigators wish to know why £310,000 from the Neopolitan diocese's Istituto per le Opere di Religione was transferred to Mr Giordano. Furthermore, they wish to know why the cardinal gave his brother a batch of six blank cheques, already signed, for a value of £161,000; and why the Opere di Religione paid out £80,000 to two nephews of the cardinal, the sons of Mario Lucio Giordano.
The investigators would also like clarification on monies paid out of the cardinal's private account at IOR, the Vatican bank, again to his brother.
The cardinal has vehemently denied any malpractice, arguing that the money lent to his brother amounts to less than the above and came from his "lifetime's savings", while the payments made to his nephews were for professional services rendered to the diocese (one nephew is an architect, the other a builder).
The cardinal also pointed out that the archdiocese of Naples is, after Rome and Milan, the third largest in Italy, with 1.5 million faithful, 284 parishes, 500 priests and 54 charitable institutions. Such a diocese handles an annual £2.5 million budget and, as cardinal, he could not possibly be expected to know just where every lira ends up.
This investigation not only poured fuel on an ongoing Italian debate about the controversial powers of investigating magistrates, but it also touched the delicate nerve of church-state relations, with the cardinal arguing that the terms of the Concordato between the Italian state and the Holy See had been violated.
While figures such as the ex-communist mayor of Naples, Mr Antonio Bassolino, and Cardinal Ruini, president of the Italian Bishops' Conference, rushed to the cardinal's defence, the Prime Minister, Mr Romano Prodi, defended the magistrates.
On Thursday, the Vatican's "foreign minister", French Cardinal Jean-Louis Tauran, summoned the Italian ambassador to the Holy See for a verbal expression of the Vatican's concern about possible infringements of the Concordato.
Significantly, however, the Vatican's chief spokesman, Dr Joaquin Navarro-Vals, pointed out that the Holy See's protest did not touch on the accusations levelled at Cardinal Giordano.
In his initial reaction to the affair last week, Dr Navarro-Vals had been especially circumspect, saying only the church was "close to every bishop in moments of joy and of trial and is following the case closely". Vatican sources suggest the cardinal's handling of the affair has not won universal Holy See approval. Not only would the Vatican have preferred to avoid a public church-state clash, but the cardinal's comments regarding his phone being tapped - "I might have been on the phone to the Pope" - infringed an unwritten Italian church code.
For a start, Vatican sources suggest, one does not gratuitously drag the Pope's name into extraneous affairs and, secondly, everyone knows only too well that the ageing and enfeebled Pope John Paul does not these days pick up the phone to talk to the cardinal of Naples or, indeed, to anyone else.
Even in Naples itself, where public opinion seemed to be strongly on the cardinal's side, there were those who questioned his handling not only of the investigation but also of church funds.
Ciro Castaldo, leader of a local Christian group, told reporters the cardinal might have been imprudent in his use of church funds, adding that perhaps he should not have been so critical of the investigators. "It would have been far more evangelical to accept everything as it came, especially as it is presumed the cardinal is innocent."