But a spontaneous confession to a Milan court by the small-time criminal who chauffeured Gucci's killer to the leatherwear magnate's office on the fatal morning has turned the trial upside down.
Benedetto Ceraulo, who has spent 18 months behind bars charged with pulling the trigger, was not the murderer, said driver Orazio Cicala in his testimony. The real killer is still at large and, if Mr Cicala has his way, will remain so: "I'm naming no names," he told the court. "I've got a wife and family to protect."
Mr Cicala's confession left both prosecution and defence gasping on the first day that all those accused of involvement in Gucci's murder were present in the court room.
Ms Reggiani sobbed and coughed through the ordeal, her former best friend Giuseppina Auriemma remained impassive, as did Ivano Stavioni, the man whom Ms Auriemma allegedly contacted to arrange for Gucci's removal. If Ceraulo allowed himself a smirk of relief no one noticed.
All eyes were on Ms Reggiani who, since her arrest in January last year, has insisted her well-publicised hatred of her former spouse was never intended to end in bloodshed.
And if she told all and sundry that she would like to see Maurizio dead, it was no more than a way of verbalising her resentment over Gucci's high- handed treatment of herself and their two daughters, Ms Reggiani wrote in a memorandum sent to judges last month.
According to that account, Ms Reggiani never dreamed anyone would take her at her word. According to Mr Cicala, Gucci's ex-wife made very sure her wishes came true.
"Stavioni and Ms Reggiani came to my house, and she promised me lots of money even if things went badly," he told the court.
Mr Cicala said he hesitated at first, mulling over the possibility of recording a conversation with Ms Reggiani and using it to extort money from Gucci.
But Mr Cicala had loan-sharks breathing down his neck, and Ms Reggiani came up with the money quickly. "I met her a while later in the Jamaica bar in Milan. She asked me to speed things up," he said.
Shortly afterwards Ms Auriemma phoned to inform him that it was time for action: "The parcel has arrived," she announced.
The next day, at 8.35am, Gucci was hit by four bullets as he entered his office in central Milan. The killer, whom no one saw clearly, made off in a car which has never been found.
It was months before investigators' suspicions homed in on Ms Reggiani. The Guccis, famous for their truculence, were not short of enemies.
Initial inquiries focused on Maurizio's dodgy business dealings since selling off his 50 per cent stake in the family luxury leather goods family in 1993.
Ms Reggiani's possible motives for wanting her husband killed were numerous: in 1992 she had had a massive brain tumour removed in an operation which left her prone to epileptic fits and periods of memory loss: her husband was highly unsympathetic throughout her illness, she has said.
Then in 1994, the Guccis went through an acrimonious divorce, after which he neglected his daughters. At the time of his murder, Gucci was reportedly about to marry his companion, Paola Franchi, in a development Ms Reggiani feared would deprive their daughters of their inheritance.
Ms Reggiani's lawyer, Giovanni Maria Dedola, has argued that there is an abyss between saying you would like to see your ex-husband dead and actually ordering his murder.
Moreover, he added, "my client is a seriously ill woman, and quite incapable of making such a dreadful decision".
After Mr Cicala's confession, he will have a much harder time proving his case.