Helsinki police forensic tests did not provide any information about the unknown substance that was spread inside the Hotel Torni in July.

On 8 July, a patron of the hotel's rooftop Ateljee bar spread the unknown substance throughout the establishment, causing health problems for some staff members.

Police will the preliminary investigation of the case, and it will not be taken into consideration of charges.

"Several samples were examined in the laboratory, but it could not be shown that any were the substance spread in Torni. The substance apparently evaporated quickly on the spot," the investigator in charge, Detective Inspector Crista Granroth told Yle.

Suspect did not know what she was doing

The police caught the roughly 50-year-old woman who spread the mystery substance a few days after the incident.

At first, she was not allowed to be questioned by police for health reasons. According to Granroth, when they got to the interrogations, no crime was revealed.

"The suspect had not understood that her actions could cause health symptoms to anyone. Based on the preliminary investigation, the suspect did not intend to cause damage," Granroth clarified.

The police also searched, among other things, the suspect's home, but nothing suggestive of a crime, such as the distributed substance, were found.

"It should be emphasised that the substance in question has not been known to be a generally dangerous or toxic substance. Some compounds may cause symptoms for some and not for others," Granroth pointed out.

Initially the crimes in the preliminary investigation were aggravated assault, causing damage and causing serious danger to life or health of another person through recklessness or carelessness.