Now it's a murder case: suspect held over missing oil executive Carole Waugh

Man said to have posed as brother of Carole Waugh arrested at Luton Airport

Carole Waugh was last in contact with her family in April (PA)

A man believed to have posed as the brother of the missing businesswoman Carole Waugh was being questioned last night on suspicion of killing her.

Ms Waugh, an oil executive who had been based in London since 2008, was last in contact with her family in April. Scotland Yard said yesterday that new information had come to light and detectives were now treating the case as a murder inquiry.

Concern had been growing that Ms Waugh, 50, was abducted after at least three women were believed to have tried to steal her identity in an attempt to plunder thousands of pounds from her bank accounts. A man pretending to be her brother also brazenly walked into an estate agency and attempted to sell her £675,000 flat.

The 47-year-old British man was arrested as he arrived at Luton Airport on Tuesday night. He was originally arrested for conspiracy to defraud and kidnap. Police declined to say which country he had flown in from.

Ms Waugh has been living at a flat in Marylebone, central London, after returning to Britain following an eight-year spell as an oil executive in Libya. Scotland Yard said last week that an examination of her private life since her disappearance suggested she may have been leading a double life as an escort. Officers appealed for any men who might have contacted her over the internet to come forward. Police had been trying to contact her circle of friends, including people she planned to travel with to Las Vegas. Her family, who made a series of emotional pleas for her return, said they knew little of her life in London.

She was last seen after she visited her family in County Durham in April when they discussed plans for her 50th birthday. Concerns were raised after she stopped her regular calls home to her mother and she was reported missing in early May. As well as money going missing from her accounts, other personal items disappeared. Yesterday, police released pictures of Cartier jewellery she wore, including a white gold bracelet and a ring.

Detective Chief Inspector John McFarlane, of the Met's homicide and serious crime command, said: "Information has been received which has progressed this inquiry and we are now treating Carole's disappearance as a murder investigation.

"I am unable to go into further detail about the nature of the new information at this time, however, we now believe that Carole has not been seen alive since 16 April. Since that time, significant plundering of her estate has taken place to the value of hundreds of thousands of pounds.

"In addition to a number of fraudulent transactions associated with Carole's bank account there are also a number of her personal possessions that currently cannot be located." A total of 10 people have been arrested in connection with the inquiry, including two men caught on security-camera footage removing money from a cash machine at a Sainsbury's store in Enfield, north London, where Ms Waugh's card was used.

Ms Waugh had taken on a series of short-term contract jobs since her return from Libya in 2008 but was comfortably off and did not need to work regularly, according to the police.