A parliamentary commission of inquiry into Italian terrorism is planning to take evidence this autumn from Mr Romano Prodi.
The inquiry will focus on a bizarre quirk in the most famous Red Brigades kidnap case, which ended in the murder of Christian Democrat leader Aldo Moro in 1978.
The hearing could prove an embarrassing ordeal for Mr Prodi, as it concerns an alleged spiritualist seance attended by the President-designate of the European Commission some 21 years ago.
"He is one of the first people we intend to question," said Senator Giovanni Pellegrino, the commission's chairman.
"As a member of parliament he cannot be forced to attend, but Mr Prodi has written to me expressing his willingness to give evidence."
Today, the episode would be entirely forgotten if it were not for Mr Prodi's involvement and the fact that the "ghost" provided a clue that might have led to the liberation of Mr Moro, the Christian Democrat Party leader who was a prisoner of the Red Brigades at the time.
The seance took place on April 2nd, 1978, at the holiday home of Prof Alberto Clo near Bologna. Mr Prodi was among seven academics from Bologna Univeristy who decided to spend a rainy afternoon gathered around the ouija board.
Asked where Mr Moro was being held, the spirit gave a number of answers: Viterbo, Bolsena and Gradoli, all towns in northern Lazio. But Gradoli, it would later emerge, was also the name of the Rome street where the head of the Red Brigades was then living.
Unfamiliar with the name and surprised at the spirit's insistence on it, Mr Prodi passed the tip to a contact at Christian Democrat Party headquarters in Rome. Four days later police raided the town of Gradoli.
No evidence of a Red Brigades presence was found, but on April 18th, thanks to a deliberately flooded bathroom, police discovered a Red Brigades base in Rome, at Via Gradoli 96.
Better used, the tip-off from the spirit world could have led to the arrest of Mario Moretti, the mastermind of the Moro kidnap. The bullet-riddled body of the Christian Democrat politician was found in the boot of a car in the capital on May 9th, 1978.
Senator Pellegrino and other members of the parliamentary commission believe the seance story was invented to avoid revealing the identity of Mr Prodi's informant.
"I consider it grave that the participants are still holding to this version after so many years," he said. Those present at the seance have confirmed Mr Prodi's active participation and their belief that they witnessed a paranormal phenomenon.
"I witnessed an inexplicable event," Prof Clo told the commission last year. "The saucer moved with extraordinary rapidity, just as it was extraordinary that it stopped on the letters." According to Mr Enzo Fragala, a commission member for the far right National Alliance, Mr Prodi faces a humiliating grilling.
Like Mr Pellegrino, he does not believe in ghosts and calls the seance story a "vulgar mystification".
"By concealing their source, they damaged the investigation. If the source had been revealed, investigators would have arrived at Via Gradoli immediately."
Mr Fragala said it was unthinkable for a group of Catholic intellectuals like Mr Prodi and his friends to be dabbling in the occult.
"It's like saying they decided to organise a sexual orgy," he said. "These were all serious economists, who believe in seances as much as journalists believe in fairies. Prodi will cut a truly miserable figure when he comes here, just as his colleagues have already done."