The murder and mutilation of courting couples over nearly two decades was a saga that was thought to have ended with the fatal heart attack of Pietro Pacciani, the farm labourer convicted of the crimes.

He would disappear into a landscape of woods and vineyards on moonless nights to collect gruesome trophies with a .22 Beretta revolver and a knife.

The first to die, in August 1968, were Antonio Lo Bianco, 29, and Barbara Locci, 32, who were shot in a car at point-blank range on an isolated lane on a week end. A pattern was set. Another seven couples were to die, the last in September 1985.

Pacciani, stocky and tough, was convicted of the crimes in 1994 and died four years later. Italy consigned the case to history. Except that last week evidence surfaced suggesting Pacciani was not the Monster. He was merely the delivery-man to a Satanic sect, which commissioned the murders to obtain human body parts for ceremonies, said investigators.

The real monsters were allegedly the wealthy and respected members of Tuscan society - including a doctor, ambassador and an artist - who to this day have remained undetected. A cover-up involving secret service agents and missing money is now said to be unravelling.

Last week detectives from Florence raided the homes and offices of Aurelio Mattei, a psychologist with the secret service, Sisde, and of Francesco Bruno, Italy's leading criminal psychologist.

Computer disks, books and notes about the killings were confiscated and both men were questioned for up to nine hours.

Neither is a murder suspect and they have not been charged, but detectives believe they may have withheld evidence from the original investigation into Pacciani, for which they were retained as consultants.

In 1992 Mattei wrote a book, Rabbit on Tuesday, which anticipated evidence uncovered only since the investigation was reopened earlier this year.

Bruno, a regular guest on chat shows, outlined the theory of an occult sect in a report commissioned by the secret service in 1985 - before the final killing. He sent it to Vincenzo Parisi, who has since risen to head the service, but the report was never forwarded to police.

The head of Florence's detective force, Michele Giuttari, discovered its existence only recently, after groping towards the same theory.

The report suggested the mutilations - the women's left breast and pubic area were removed - could have been used in occult ceremonies and even told of a remote villa where they could have taken place.

Pacciani worked as a gardener in Villa Verde, a former nursing home, which police belatedly searched in 1997.

Giuttari wants to know why the secret service buried the report during a parallel investigation, which spent hundreds of thousands of pounds from a 'black fund', of which no records were kept.

Giuttari hopes that following the money trail could lead to a breakthrough by revealing suspects who were protected by Sisde. 'We will clarify everthing and in good time,' he said. Two members of the secret service have been questioned.

Detectives never closed the investigation, even after Pacciani died and two of his friends, Mario Vanni and Giancarlo Lotti, were convicted for helping him. There were too many loose ends.

Pacciani's conviction was overturned and he was facing retrial when he died. The original verdict of a heart attack has been discredited and his death is now being treated as murder. The investigating magistrate, Paolo Canessa, believed Pacciani's heart attack in February 1998 was triggered by drugs to silence him lest he reveal the real monster, or monsters.

Giuttari thinks the illiterate labourer's unexplained wealth - two houses and £50,000 in the bank - were payments from the sect. The leader is thought to be a doctor.