Swedish police questioned several people today in connection with the murder of Foreign Minister Anna Lindh, but none was named a suspect.
The Foreign Ministry revealed that the mother-of-two had recently received six letters and e-mails, some with "harsh language."
The letters were not considered threats on her life at the time and were not given to police, a ministry spokesman said.
In the wake of Lindh's death, however, all correspondence sent to her in the last few weeks was being examined, said Margareta Linderoth, a spokeswoman for Sweden's security agency, or Sapo.
The murder of the 46-year-old came four days before Swedes vote in areferendum on adopting the euro. She was a leading campaigner for replacing the krona with the EU common currency - an issue that had inspired vehement opposition.
Analysts said her death would likely help the yes campaign.
Police said there was no evidence the attack was related to the euroreferendum.
One opinion poll today had the yes and no sides even, while another gave no voters held a 12 per cent lead.
Both were conducted after Lindh's murder. The authorities widened theirsearch for a stocky acne-scarred man who witnesses said stabbed Lindh in the stomach, chest and arm in a Stockholm department store on Wednesday.
Police checked homeless shelters and hotels, among other locations.
A number of people were taken in for questioning, police spokeswoman Agnetha Styrwoldt-Alfheim said.
A 32-year-old man that Swedish media said was a possible suspect had been released and was not involved in the killing, she said, adding two other men were questioned and also released.
Police spokesman Leif Jennekvist surveillance tape from another floor of the seven-storey department store where Lindh was stabbed may contain footage of the main suspect.
"There's a person on it that could match the descriptions that we have from the scene of the crime," he said, adding the footage was grainy. The footage is apparently before Lindh was attacked.
Throughout Stockholm, impromptu memorials of roses sprang up by billboards bearing Lindh's picture for the euro campaign.
In front of the department store where she was killed, hundreds of candles were lit overnight and the mound of lilies and roses stood more than three feet high.
Lindh was honoured in church services, and the imam of Stockholm's mosque, Hedi Arfaoui, said its Friday prayer service was dedicated to her.
AP