Russian police are intensifying their operations to find evidence that could lead to the arrest of those who killed the popular liberal politician, Galina Starovoitova.
Investigators have raided hundreds of night clubs and casinos in St.
Petersburg where the murder took place.
Several hundred people were reported to have been arrested, many of whom were wanted by the police for other crimes.
Earlier, the Russian authorities said detectives were making progress in the case because of the unprecedented help they received from the public.
Mrs Starovoitova was shot dead in her appartment building over a week ago.
Her death caused a public outcry in Russia with leading politicians describing it as an attack on democratic values.
From the newsroom of the BBC World Service