Italian forensics experts on Monday took DNA samples from the surviving relatives of Mauro De Mauro to test a Mafia informant's claim about a body in a Calabrian graveyard.
The informant says the body is that of the famed investigative journalist and not a local Mafioso.
De Mauro disappeared in 1970 after claiming to have a scoop on the death of maverick Italian oil chief Enrico Mattei.
Police believe the Mafia killed him because he knew too much about Mattei's death.
Proving that De Mauro was killed and buried under the name of a Calabrian boss is expected to shift attention from the Mafia's top bosses, who have been already been indicted for the murder, to those of its Calabrian sister the 'Ndrangheta.
On Monday police teams took saliva in Palermo from De Mauro's daughter Franca and at Rome University from his brother, Italy's leading authority on linguistics.
''We should have the results in about a week,'' said the Catanzaro prosecutor who ordered the tests.
''Even though the family are skeptical, we think the informant's tip-off is reliable''.
The informant told police in September that De Mauro was not killed by Cosa Nostra, as previously thought, but by the 'Ndrangheta.
The informant claimed the body of an 'Ndrangheta member buried in a cemetery near Catanzaro was in fact that of De Mauro.
When it was found in the countryside before being buried, the unrecognisable body was identified only on the strength of a belt.
Catanzaro's Anti-Mafia Department ordered the exhumation of the body, buried under the name of Salvatore Belvedere.
De Mauro went missing in September 1970 while preparing a famous film on Mattei's death which suggested the Mafia put a bomb on the oil executive's private plane before it crashed in 1962.
The informant who told police the body was De Mauro said he got the information from an 'Ndrangheta boss killed in 1984.
On the night before he disappeared, De Mauro told a friend he had important new information on the Mattei plane crash.
De Mauro was doing research for Francesco Rosi's landmark film, 'Il Caso Mattei' (The Mattei Case), starring Gian Maria Volonte'.
Italy's most famous Mafia turncoat, the late Tommaso Buscetta, claimed the famous boss of state fuels group ENI was killed to stop him treading on the toes of the so-called Seven Sisters of world oil.
Mattei is known to have angered the world's biggest oil companies by forging deals in North Africa, Russia and Iran that aimed to make Italy independent of Big Oil.
An investigation into the plane crash concluded it had been caused by a technical fault but another probe, 30 years later, said a bomb had exploded on board.
The prosecutor in the case said recent investigations had unearthed an ''institutional cover-up'' in the initial probe into De Mauro's disappearance.
Buscetta and other leading Cosa Nostra turncoats say the Sicilian Mafia killed De Mauro.
The Mafia's former boss of bosses, Toto' Riina, is on trial in Palermo for the murder.
Riina's successor until his arrest last year, Bernardo Provenzano, is under investigation in a separate probe into the murder.
Some experts contend that De Mauro's death was not connected to his knowledge of how Mattei died.
They say he was given a Mafia death sentence because he had found out about about a neofascist coup to be staged in Rome in December 1970 by his former WWII commander and boyhood friend Prince Junio Valerio Borghese.
According to Mafia turncoats, the coup was aborted at the last minute after key establishment figures withdrew their support.
