'We are determined to catch them and gather the evidence for prosecutions'
From placing surveillance equipment under cars to using false identities to steal personal data from State bodies - the techniques used by private investigators are as varied as they are staggering.
During an investigation that dates back to 2014, Assistant Data Protection Commissioner Tony Delaney has almost single-handedly uncovered the murky - and at times disturbing - activities of these so-called detectives.
Now in charge of a new special investigations unit based in Co Laois, Delaney's message to private investigators is clear: "If you break the law, you will be caught."
Giving a rare insight into the work of his office, Delaney tells the Irish Independent that he is embarking on an investigation that is both unprecedented and ground-breaking.
He has established that private investigators are now being hired by a raft of bodies, including banks, credit unions, debt collectors, car finance companies, local authorities, and law and insurance firms.
Many of the 120 registered private investigation firms are not suspected of doing anything illegal. But others are and will be prosecuted, the Assistant Commissioner vows.
"The era of private investigators being able to unlawfully access personal data from State databases - and get away with it - are over. They will be caught. We are determined to catch them and we are determined to gather evidence to prosecute them. It's a zero-tolerance policy," Delaney says.
Delaney has obtained evidence already that some of the largest State databases - those belonging to the HSE, An Garda Síochána and the Departments of Transport and Social Protection - have been infiltrated by private investigators. In some cases, they use false identities or 'blagging techniques' to illegally obtain personal data that they sell on for a fee.
"We consider this to be of the most serious and egregious form of breach. It's deliberate, it's intentional," he said.
Delaney is also investigating cases where State employees knowingly hand over information to private investigators or intermediaries working on their behalf.
"Staff in particular agencies have been giving information to private investigators who are known to them and have been approached on that basis," Delaney reveals.
Delaney makes clear that not all private investigators are involved in illegal activities. He also stressed that individuals within the insurance sector were taken aback when he informed them of the use of tracking devices.
But he says it is a far more time-effective way - from the investigators' perspective - of tracking the movements of customers to determine whether they have made false insurance claims.
"The private investigator can watch from their mobile when a person is on the move ... instead of sitting outside of their house for several hours or days," he says.
The objectives of Mr Delaney's wide-ranging probe are five-fold.
Firstly, he wants to stop the offending behaviour by the private investigator and to ensure the organisation that has been targeted takes appropriate action.
But he also wants to gather enough evidence to prosecute, and to alert members of the public whose data has been breached.
Finally, he is determined to raise awareness in State bodies about the prospect of falling victim to the blagging techniques and illegal tactics used by private investigators.
"The cases we are interested in, and what we learn from the 2014 cases in particular, is that some operators do use tactics that are unlawful and we need to deal with that," he says.
"This is a ground-breaking investigation, and in my opinion we will uncover many more cases of inappropriate or unauthorised access to personal data held on State data bases over the course of the next year or two," Delaney adds.