A senior WA police officer is accused of illegally monitoring the girlfriend of a fellow officer by placing a matchbox-sized GPS tracker on her car so they could check on her movements while they were away on holiday.
The two officers, who were friends and colleagues, were going on a pig-shooting holiday together to the far north of WA in September 2012.
Perth Magistrates Court was told today that the night before they left, the Itrail tracking device - which was held in a magnetic case - was secretly placed on the woman's Ford Fiesta.
When the officers returned, a data log from the GPS tracker was allegedly downloaded and emailed by one of the detectives to the officer who was in a relationship with the woman.
The report logged journeys she had made on every day they were away.
The Corruption and Crime Commission launched an investigation last year, and found the GPS tracker in the officer's house, and found relevant text files on his computer.
The boyfriend of the woman, who is still a serving police officer, this morning pleaded guilty to one count of unlawful use of a tracking device.
The second officer denies five charges of illegal possession and use of the tracker, and went on trial today.
Prosecutor Alan Troy told the court that the woman had never been investigated or convicted by police, and as of yesterday had never been the subject of any police intelligence.
Seamus Rafferty, lawyer for the officer denying the charges, admitted his client had obtained and fitted the GPS tracker to the woman's car, as well as printing out the report when he returned to work.
But Mr Rafferty said it was done in the course of the detective's duty, with the tracker being used as part of a preliminary investigation into suspicions the woman had drug associations.