Police have arrested four people in Gurkovo as part of a Sofia police investigation into tracking devices, the Sofia Directorate of the Interior (SDVR) told BTA. No charges have been brought against them yet.

The four are aged between 31 and 54. Police are checking how they are linked to the case, which the Sofia directorate is handling.

SDVR has opened pre-trial proceedings over a special technical device that was used illegally to gather information without permission. The complaint came from the people who were targeted with the devices.

Chief commissioner Nikolay Peltekov, head of SDVR, told reporters that expert examinations will show what the tracking devices were used for. He said the victims had suspicions, and SDVR itself found the devices.

Peltekov said a complaint has also been filed with the regional interior ministry directorate in Stara Zagora, but the first one reached SDVR, so the case was opened there.

The results of the examinations will be reported, and the files will then go to the Sofia District Prosecutor's Office.