The RCMP has confirmed it used a controversial spy technology to identify and locate mobile devices during 19 criminal investigations last year -- the first public acknowledgement that the force tracks such data.

The RCMP said in a release Wednesday that use of its so-called Mobile Device Identifier (MDI) devices are in full compliance with Canadian law, including the Charter of Rights and Freedoms, and require judicial approval, except in “extremely urgent cases” to prevent death or immediate harm.

The statement, which refers to MDI technology as an “important investigative tool,” notes that private communications such as emails, text messages, phone calls, images, and contact lists are not being collected by RCMP investigators, and only a limited number of authorized personnel have been trained to use the devices.

“When a trained officer deploys MDI technology, it attracts and momentarily connects cell phones in the immediate proximity, before returning them to their own networks. The technology collects International Mobile Subscriber Identity (IMSI) and International Mobile Equipment Identity (IMEI) data associated with the phones, allowing the operator to identify the phone used by the suspect,” said the force in the statement.

IMSI and IMIE data are internationally standardized unique numbers that identify a mobile subscriber and device, respectively.

Collected data is said to be stored on an isolated system that can only be accessed by those who manage the technology.

The RCMP said data that is not relevant to the specific investigation is immediately sequestered by the operator and not shared with investigators. The data is said to be destroyed after court proceedings, appeal periods, and any specific order from a judge.