An Apple Inc. tracking device was found attached to an unmarked police vehicle in central Japan, leading to suspicions that a yakuza crime syndicate was responsible, investigative sources said Wednesday.

Police are alleging a crime organization planted an AirTag, a device marketed for use in locating personal belongings, on the vehicle to track the movements of investigators, the sources said. The vehicle on which the tag was planted is used to investigate crime syndicates and drug crimes.

The commercially available device was found in a black plastic box, attached to the muffler of the vehicle, in May by an investigator who was getting into the car in the parking lot of Toyota police station in Aichi Prefecture.

The parking lot is open to the public. There have been no reports of AirTags being found on other vehicles, the sources said.

The device is about 3.2 centimeters in diameter and sends out a Bluetooth signal that can be detected by a nearby phone or similar device. Using an iPhone app, the owner can then determine the location of the tag which can be attached to items like wallets or keys.

Following the incident, the Aichi Prefectural Police issued a directive telling officers to sweep their vehicles to ensure that no suspicious items have been attached to them.