The lawyer of a British aristocrat missing in the south of France said his client had been worried about "strange things happening to him".
The Earl has not contacted family or friends since 5 November
He spoke of his growing concern for the 66-year-old 10th Earl of Shaftesbury, who vanished more than two weeks ago.
"The earl is extremely generous to his friends and may have been taken advantage of," said Thierry Bensaude.
The Dorset earl divides his time between homes in the City of London, Hove seafront, and the French Riviera.
M Bensaude said he did not believe the peer had taken his life or gone into hiding.
He contacted local authorities after the earl failed to get in touch.
"He usually calls me every few days so it is very mysterious," he said.
"He is a generous and distinguished man who falls in love easily and meets people in bars who are as far removed from his social background as it is possible to be."
It is understood the earl is taking legal action in relation to a theft.
His girlfriend, a 33-year-old Cannes hostess who has not been named, told local newspaper Nice Matin she believed "something has happened" to him.
"We met very simply, he told me his life and I told him mine - this meant security for me and my children after difficult years," she said.
"I don't know any woman who wouldn't have pursued such a man."
The three-times married earl, whose full name is Anthony Ashley-Cooper, arrived in Nice on 3 November.
He checked in to the £130-a-night 4 star Noga Hilton in Cannes on 6 November for one night and has not been seen since.
Sussex and City of London police were involved in the initial stages of the investigation, which is now being led by French police.
The earl's second wife Lady Shaftesbury, who lives at the family seat in Wimborne, Dorset and is the mother of his two sons Anthony and Nicholas, said they were all "extremely concerned".
His sister Lady Frances Ashley-Cooper left her home in the south of France on Saturday to join the family in England.