The story duly appeared in his newspaper, La Repubblica, and he braced himself for an avalanche of calls from the police, the magistrature, politicians and fellow journalists. But nothing happened. Not a single phone call. The whole country had supposedly been hunting high and low for the apartment that turned out to be in Via Montalcini in the southern part of the city, but now nobody seemed to care.
Things got weirder. Two years later, the Interior Ministry announced that it too had discovered Moro's prison, but let everyone, including the hordes of journalists who rushed to the scene, believe it was at quite a different address. They were sent to a tiny bedsit that happened to belong to the same owner as the Via Montalcini flat, a Red Brigades member, Anna Laura Braghetti.
Villoresi dug further and discovered that the police had known about Via Montalcini right after the kidnap but, bafflingly, chose not to raid it, even though two of Moro's captors were still living there. A van stuffed with electronic surveillance equipment - almost certainly belonging to the intelligence services - had been parked across the street and may even have been there during the kidnap itself.
Again Villoresi wrote up his discoveries in La Repubblica, and was not paid the blindest bit of notice. Over the next few years, as his discoveries were fully vindicated, he openly accused magistrates and politicians of lying about the Moro affair, but was not even given the pleasure of a libel writ. He was simply frozen out by a wall of official silence, and eventually gave up his high-profile reporting job, a deeply disillusioned man. "They've won and I've lost. All those people involved in the Moro affair, they all went on to glittering careers. Anyone who tried to play it straight got burned," he said.
As the 20th anniversary of the most shocking incident in postwar Italian history approaches - Moro was captured on March 16, 1978 - none of the really troubling questions about the affair have found an adequate answer. Why, in a notoriously soft-hearted country like Italy, was no serious attempt made to bargain for Moro's life? Was it an uncharacteristic determination not to make deals with terrorists, or did it suit the establishment to see Moro dead?
How come every other major crime committed by the Red Brigades has been reconstructed in painstaking detail, and yet the Moro affair is still riddled with holes, inconsistencies and attempted cover-ups? Were the police merely incompetent, or did they really decide not to find Moro and save him while they could? Why have the major players in the crisis - senior Christian Democrats like Francesco Cossiga and Giulio Andreotti - chosen to remain silent?
"The Moro affair has produced nothing but lies and false leads. I don't think it is possible any more to find out what really happened," Villoresi said. "Certainly, there are people who know the truth, but we will never know if they are telling us the truth."
Moro was kidnapped on the day that his long-cherished political dream was due to be realised: the formation of a government of national unity, including - for the first time since the war - the participation of the Communist Party. Italy in the 1970s was buffeted by an extraordinary array of anti-democratic forces, including terrorists from both political extremes, the secret P2 Masonic lodge that plotted an authoritarian takeover, and semi-autonomous intelligence service agents who were putting spanners in the normal workings of politics and the judiciary.
Moro recognised that his own party, the Christian Democrats, was largely discredited after 30 uninterrupted years in power, and that the powerful Communist opposition could not be ignored much longer without running the risk of open guerrilla warfare on the streets or an authoritarian coup. His big idea was a "historic compromise" that would blend the Christian Democrats and the Communist Party into a centre-left coalition. The plan was highly controversial in his own party's ranks, and it terrified the US government as Italy was a frontline Nato state in the Cold War.
So when a guerrilla commando stopped Moro's car a few hundred yards from his home, killed his five bodyguards and whisked him off into captivity, the country was plunged into a state of such panic that anything could have happened. Beyond the humanitarian concern for his well-being was the risk that the Christian Democrat party, or even the state, could simply dissolve.
Moro's party colleagues, particularly the newly-sworn-in Prime Minister, Giulio Andreotti, had to decide whether the risk of subversion was greater with their party president dead, or ransomed but alive. Perhaps the most persuasive political logic of the time was expressed by the journalist and historian Indro Montanelli, who argued that if Moro were to return in a blaze of glory (after a police raid to free him, say) it would give enormous impetus to the historic compromise and lead to Italy abandoning the Western alliance. "But if Moro is eliminated physically ... or if he returns after a humiliating negotiation process, things can go differently," Montanelli said.
And so they did. The Christian Democrat leadership flatly rejected attempts at mediation, and the police launched a dragnet operation that consumed extraordinary quantities of men and hardware but achieved very little.
Tip-offs on key Red Brigades hideouts were either ignored or followed up so late as to be useless. When the name Gradoli came up in the investigation, for example, police virtually ransacked the village of that name in the countryside near Viterbo. But they ignored the Via Gradoli in Rome where an apartment, already denounced as suspicious by the neighbours, held a welter of important material left by two of the kidnappers. When Moro's wife queried the police on this point, she was told there was no Via Gradoli in Rome. (It later turned out the police not only knew about the flat in question, but had failed to carry out orders to search it.)
After Moro's body was found in the back of a Renault 4 at a point equidistant from the headquarters of the Communist and the Christian Democrat parties, the obfuscation only increased as everyone tried to cover up for their failings. A shady investigative journalist who hinted at dark secrets held by Mr Andreotti over the Moro affair wound up with a bullet in his head; Mr Andreotti is currently on trial for his murder. Carlo Alberto Dalla Chiesa, the Carabinieri general who dismantled the Red Brigades and arrested its leaders, was sent to Palermo as prefect and was killed by the Mafia shortly afterwards; it is widely suspected he was sent into a death-trap because he knew too much about Moro.
As the anniversary approaches, there is much talk of an amnesty for left- wing terrorists, the idea being that the world has moved on, the Cold War is over, and many of the leading Red Brigades exponents have been in jail for a very long time. But Luca Villoresi believes the main motivation behind an amnesty would be to bury the skeletons of the Moro affair once and for all. "How come the terrorists were sent to jail, but not a single investigation was ever launched into the magistrates and police officers who lied, failed to carry out orders and actively participated in covering up? That's not a question you hear many people daring to ask."