Detectives believe the missing shoulder bag may have contained a detailed list of the Colombian-born woman's customers. They have warned prostitutes working in the area to be on their guard in case the killer strikes again.
The body of Mrs Koppell, 39, was found by her English husband in the bedroom of her ground floor flat in York Mansions, Chiltern Street, on 8 August. She had been stabbed many times with a broad-bladed kitchen knife.
Mrs Koppell, who often worked under her maiden name of Luz-Marina Gomez de Rubio or the pseudonym Luz-Marina Angarita, was last seen by cashiers inside the Midland Bank in Baker Street, near her home, at 1.43pm on the day she died.
About 4am that morning she was spotted leaving the Victoria Casino in George Street, Marble Arch. A keen gambler, it was one of her regular haunts.
Mrs Koppell, who had long dark hair with blonde streaks, was 5ft tall and of medium build. She wore black leggings, high heels, a white suit jacket and sunglasses.
Witnesses said she had been carrying her black Moschino shoulder bag, thought to contain her client list, on the day she died.
She had run her operation from the two-bedroom flat, where she had lived for just two weeks before her death, and had advertised using cards placed in telephone boxes.
Mrs Koppell had also worked as a masseuse, advertising in London listing magazines, and had many legitimate clients. She ran her business herself, preferring not to use the services of a pimp or a maid. She had lived in London for 13 years and had worked as a prostitute for several years.
'She was not a common prostitute and it is thought that many of her clients may have been upmarket,' said a police spokesman.
Her husband, who lived separately, disapproved of her lifestyle. He discovered the body after being unable to contact her on her mobile telephone.
Police, who have set up a control room in Chiltern Street, believe Mrs Koppell died between 5pm and 10.30pm. There were no reports of shouting or screaming from the flat.
Police believe Mrs Koppell had let her killer into the flat, which had good security.
A spokesman said: 'It was a frenzied attack. She died of multiple stab wounds. The manner in which she was attacked suggests that it was more than just a quarrel or a falling out.'
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