They found large stashes of cash, gold watches, jewellery and firearms. They sequestered several properties, including villas, a petrol station, and a bar, with the property amounting to €20m.
The inside information leading to the arrests came from four informers, including two ex-wives of two members of the clan, which is of Romany Gypsy origin and has long been accused of drug-running, racketeering and usury in Rome.
"The different branches of the family are jealous of each other, but when there is a problem they come together, united," one of the ex-wives was quoted as saying. "They are like a wolf pack. That's how they work."
There were few details about the two ex-wives but women who have turned against the clan and become "pentiti" or informers in the past have spoken about how they were subjected to extreme control, not just by their husbands but other male family members.
One ex-wife, Debora Cerreoni, said she was beaten and threatened during her marriage to a clan member, Massimiliano Casamonica, and derogatively referred to as a "gaggia", a dialect word meaning non-Romany – similar to the "gadjo" or "gadji" used by British Romany people.
She said family members boasted of having "millions of euros" hidden in false walls in their homes.
"They ruined my life," she told a court in January. "I hadn't just married Massimiliano, but the whole clan. They threatened to dissolve me in acid."
Another of the ex-wives, Simona Zukova, originally from the Czech Republic, said the clan kept "unimaginable amounts of cash" stuffed into rucksacks and hidden in false walls in their villas.
"They always keep their money in cash - they don't use bank accounts or invest it because they always fear having it seized by the authorities, given that it had happened in the past," she said.
"They bought jewellery and watches as investments. Rolexes costing €50,000 or €60,000."
Women from the family would think nothing of spending €4000 on a handbag and when they shopped at Louis Vuitton, they would be offered Champagne, she said.
The Casamonicas regarded the city as their exclusive domain and on wiretaps, members were heard complaining that other criminal groups, such as the Camorra mafia from Naples and the 'Ndrangheta from Calabria, were trying to muscle in on their turf.
"The Neapolitans want to come to Rome, the Camorra wants to get in here, and the Calabrians want to come too," Guido Casamonica, a member of the extended family network, said on an intercepted call.
The family last hit the headlines in 2015 when they gave an extravagant sendoff for a clan elder, 65-year-old Vittorio Casamonica, which involved a helicopter dropping rose petals from the sky, a coffin borne in a black and gold carriage pulled by six black horses wearing plumes, and a brass band playing the theme tune from The Godfather.
There was a political row, meanwhile, over the release from prison of a one-eyed, far-Right gangster who was at the heart of a corruption scandal in Rome five years ago.
Massimo Carminati, 62, nicknamed Il Cecato or The Blind One, was released on a technicality after serving five years and seven months of a 20-year sentence for corruption, extortion and other crimes.
He was at the heart of a scandal in Rome dubbed "Mafia Capital" which involved widespread collusion between criminals and corrupt politicians in the awarding of public works contracts and the running of migrant centres. It resulted in a trial lasting 20 months that was held inside Rome's high security Rebibbia prison.
A former Right-wing militant who gave Fascist salutes while in jail, he lost an eye during a shoot-out with police in 1981.
The minister of justice ordered a review of the decision to free Carminati from prison amid intense criticism from some politicians, including Matteo Salvini, former interior minister and now effectively head of the opposition as leader of the League party.
Carminati is a former member of the Armed Revolutionary Nuclei, a far-Right group that was involved in the bombing of Bologna railway station in 1980, in which 85 people died.
He boasted of reigning over a "demi-world", a shadowy realm where corrupt members of the establishment encountered criminals, with himself as the facilitator. "It's like there are the living above, and the dead below," he said.
In an intercepted conversation, members of his gang discussed the effectiveness of intimidating opponents with their firearm of choice, the Russian-made, semi-automatic Makarov pistol.
