Police said yesterday that they were working on hundreds of leads and seeking 10 people for questioning over the murder of Anna Lindh, Sweden's Foreign Minister, but they admitted "no breakthrough" had been made.
The crime has shocked the nation and police are under pressure to solve the case quickly. The authorities will face acute criticism if they fail to make a swift arrest.
A police spokeswoman said they were investigating "known criminals and assailants, a group of about 10 ... there are a couple of special names we want to check".
The murder weapon has been found and two men who were questioned were later released. Thousands of pieces of information have been received since pictures of a man they want to question, taken from video surveillance footage, were given to the media.
A police spokesman said: "We would like to have even more help from the public with identifying this man in the picture. We are very anxious to find out his identity."
The video pictures show a man wearing a blue baseball cap and a grey, hooded sweater with a Nike logo.
The cameras did not capture the attack itself, which took place last Wednesday on the first floor of the upmarket NK department store in central Stockholm. Ms Lindh died of her injuries the next day.
Police have said that the man pictured fits the descriptions given by witnesses, but have stopped short of calling him a suspect. Police think the assailant has a record of violent behaviour.
Although forensic science experts worked overnight at the scene of the crime, the shop was open for business the following day, surprising many.
Some shops near to the NK department store have told Swedish papers that the police have yet to ask them for footage from their security cameras.
The attack took place only 500 metres from where the prime minister Olof Palme was shot in February 1986. His murder remains unsolved.Reuse content