Finland's National Bureau of Investigation (NBI) is working on a suspected case of espionage, due to an incident in July in which a drone entered restricted airspace at Yle's headquarters in Helsinki.
Authorities do not suspect the incident was intentional, because the drone pilot notified Yle about the collision. However, investigators have not yet interviewed the suspect.
The airspace over Yle's headquarters is restricted and using drones in such areas requires operators to obtain a special permit.
Generally, consumer models of the remote-controlled devices are programmed to automatically avoid restricted areas, usually referred to as no-fly zones.
The NBI suspects that the drone operator flew the device near Yle's broadcast tower and then lost contact with it.
When that happens, the agency explained, the drone automatically returns to the remote control device. However, the drone crashed and got stuck in the tower's mast on its way back, according to the NBI.
The device was retrieved by an employee of Digita, a telecommunications firm which works with Yle on antenna maintenance.
Investigators examined the drone's flight log and found that it had flown a few blocks away by the Mall of Tripla, then passed the Helsinki Police Department's headquarters before heading towards Yle HQ.
The incident is being investigated as a case of suspected espionage because it occurred in an area of critical infrastructure, according to the NBI.
But authorities still think that, based on current information, the incident was an accident.
Cases of suspected espionage are rare in Finland, with only a few such investigations opened in recent years.
People convicted of espionage face prison sentences ranging from a minimum of one to a maxium of ten years.
Over the past few weeks, suspicious drone sightings have been made near infrastructure sites in various parts of Finland. Yle News examined a report on the matter by Ilta-Sanomat in a newspaper roundup on Thursday.