"We would offer the maximum collaboration" and launch a full-blown probe should French judicial authorities request Italy's help in cracking the 36-year-old mystery, prosecutor Mario Mercone said.
Italian police searched through archives of murdered women as Maurice Agnelet prepared for a verdict in his trial for allegedly killing his wealthy mistress Agnes Le Roux in Cassino near Rome nearly four decades ago.
"We are looking back through our archives for anything linked to the case," a police official in Cassino said.
Local media said the police were looking through lists of unidentified women found dead in the area but all the ones found so far have since been named.
The town is best known for its mediaeval abbey of Monte Cassino on a forested hill overlooking the town and the area was the site of a famous World War II battle.
Agnelet was this week accused by his son of shooting Le Roux, 29, in the head during a camping trip to Cassino, before dumping her naked body.
Le Roux's body was never found and Agnelet, 76, is undergoing his third trial for her murder, which is expected to reach a verdict on Friday.
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