STOCKHOLM -- Investigators collected DNA from a baseball cap apparently left behind by the man who killed Swedish foreign minister Anna Lindh, but have found no match in a national criminal database, police said yesterday.

The investigators also evaluated tips after releasing photos of a man who they said matched witness descriptions of the person who attacked Ms. Lindh in an upscale department store -- a crime that shocked the country and cast a shadow over a weekend referendum on whether to adopt the euro.

Ms. Lindh was a prominent supporter of adopting the single European currency. Swedish voters overwhelmingly rejected the euro in Sunday's referendum.

"We had hoped for more tips after the publication, but maybe people will start calling us after having read today's papers," police spokesman Mats Nylen said.

Swedish authorities were unable to collect any of the killer's DNA from a knife used in the attack and have sent the weapon to an overseas laboratory for further analysis. The Forensic Science Service in Britain confirmed that it is aiding the investigation, but didn't say whether it has received the knife.

No arrests have been made since Ms. Lindh was stabbed last Thursday, but police remain optimistic.

"We have good witness testimony," lead investigator Leif Jennekvist told reporters. "We have findings discovered along the escape route. We have secured DNA traces. It is a good investigative situation."

Pictures of a possible suspect were sent to police across the continent through Europol, the pan-European law-enforcement agency. Authorities have also contacted Interpol.

Most Swedish papers published photos in yesterday's editions from the surveillance camera at the Nordiska Kompaniet department store showing the suspected attacker clad in a baseball cap and grey-hooded Nike sweatshirt. The attack itself was not photographed and Mr. Nylen said the man has not yet been identified.

Authorities have said the attack did not appear to be politically motivated.

The police have questioned and released several people.