Detectives investigating the disappearance of oil executive Carole Waugh have arrested a man following the release of CCTV footage.
Police made the arrest after an appeal to trace a man pictured standing outside a Sainsbury's supermarket in London on July 10.
A bank card belonging to Miss Waugh was used at an ATM cashpoint at the superstore in Enfield, north London.
Police say the suspect attended a north London police station.
Detectives fear Miss Waugh may have been kidnapped. At least three different women have tried to impersonate her to use her credit cards.
So far, nine people - five men and four women - have been arrested in connection with the case.
One man has pretended to be Miss Waugh's brother - Chris Waugh - and has tried to sell her flat in central London.
Miss Waugh, 50, who worked for Veba Oil in Libya for a number of years, has not been seen by her family since mid-April.
Scotland Yard's Homicide and Serious Crime team have now been called in.
The detective leading the investigation, Detective Chief Inspector John McFarlane, said financial activity linked to her identity has become "incrementally more suspicious" since she went missing.
"Ms Waugh is a successful businesswoman and her disappearance is completely out of character," he said.
"Following her disappearance, there have been a number of fraudulent transactions associated with Ms Waugh's bank account.
"We now know that, in addition to at least three women impersonating Ms Waugh, a man has also been impersonating her brother Chris and endeavouring to raise finances, including trying to sell her flat."
He said there were also a number of Ms Waugh's personal possessions that cannot be located.
"I'm very concerned for her safety and I appeal to anyone who has known her since she returned from Libya in 2008 to get in touch with us as soon as possible," he said.
Her brother Chris, 53, who lives in Cumbria but is in London to assist police with their investigation, said it was "a very distressing moment" to discover the conman had posed as him.
He said that the family were "euphoric" at the Easter party where they last saw his sister, who they were planning a birthday party for after she turned 50 in June.
She was reportedly planning a holiday to Las Vegas with female friends, and Mr Waugh appealed for them to come forward, as well as anyone who may have worked with her recently.
Anyone with information is asked to contact the incident room at Sutton on 020 8721 4205; if you wish to remain anonymous please call Crimestoppers on 0800 555 111.
