Big data at the forefront of modern Garda Síochána investigations

Aim is to ‘saturate’ divisions and specialist units with skills to use data against criminals

Even before Joe O’Reilly made what became an infamous appearance on The Late Late Show, gardaí knew they had their man.

O'Reilly had murdered his wife, Rachel (30), at their home on October 4th, 2004, in Naul, Co Dublin, but told investigators he was working in south Dublin at the time. A friend initially provided alibi evidence which appeared to back-up his story.

But when O’Reilly’s phone records were examined, things changed. They showed his phone was pinging off telecommunication masts in a manner that put him close to the scene at the time of the killing. In a case largely based on circumstantial evidence, the mobile phone data was crucial and saw O’Reilly convicted and jailed for life.

In the intervening 18 years the age of big data has truly been ushered in. The proliferation of smart phones and other devices means most of us generate a trail every day revealing our movements, activities and interests.


Within the ranks of the Garda, that big data is now being poured over every day to solve murders, pick apart gangland conspiracies and to try to predict, and so combat, emerging crime trends across the State.

When the men who abducted and tortured Quinn Industrial Holdings executive Kevin Lunney were convicted and jailed last year the conspiracy that bound them together was set out in court, not by sworn Garda members, but by civilian Garda analyst Edel Hannigan. (The three men are now appealing against their convictions and sentences).

Once she had completed her evidence, which the defence tried to block, at the Special Criminal Court, the conspirators were conclusively linked. Her data-based work and testimony wrapped up the personnel involved in the crime, the dates they were in touch and the locations and timeframe of their planning. The sheer breadth and quality of her knowledge was a long way from the simple pings of O'Reilly's phone off a few masts.


An Garda Síochána is currently looking for more Edel Hannigans. The Public Appointments Service is running a recruitment process – closing on Monday, March 21st – for crime and data analysts to join the force as civilian workers.

The competition is part of the process to significantly beef up the Garda Analysis Service so that policing is information-led, one of the key recommendations of the Commission on the Future of Policing in Ireland, which reported in 2018.

The principal officer of the now expanding Garda Analysis Service, principal officer Sara Parsons, told The Irish Times the aim is to "saturate" Garda divisions and the force's specialist units with the skills required to hoover up and harness data and turn it against those who operate outside the law.

Parsons was one of three people hired by the force in 2007 to begin the service and was promoted into her current, more senior, position in the service in 2020. Before joining the Garda she worked for the National Crime Council, advising ministers for justice, and has a background in applied social research.

She stresses that the role of Garda analysts is not simply about scrutinising crime data or information generally to spot crime trends. Instead, analysts are at the centre of crime investigations, up to and including murder inquiries.

“Let’s take a hypothetical murder case,” she says. “The analysis service is now so well embedded in the Garda organisation that in the vast majority of murder cases an analyst is straightaway looked for [by murder detectives]. They look for an analyst in the same why they would request scenes of crime, fingerprints, forensic services. They would be there as a central part, at the case conferences and so on and working around the clock with the detectives when required.”

Parsons explains that, typically, data is taken from mobile phones by cyber professionals working on the force and the analysts then begin parsing it. They assess the calls made and the phone’s location at specific times and to help build a map of who was in contact with who, when and how often before, during and after the crime under investigation happened.

As gardaí take statements from witnesses and suspects, they are fed back to the analysts, who create “sequence of events” charts mapping the timeline of a crime and any related conspiracy or cover-up.

“They are able to see if everything is an agreement,” Parsons says of the value of the charts to the analysts and investigators. “Is our CCTV corroborating what somebody has said to us in a statement or are there discrepancies there? So (the detectives) may need to go back and re-interview people if there’s apparent discrepancies. It may be used to help develop an interview strategy when a suspect is being brought in because we know where the gaps in the story are.”

Aside from analysing the data taken from phones and laptops, the analyst can also pick through bank and payment card records and even road toll payments.

Links between data

At present a Garda analysis team works full-time in the Dublin Metropolitan Region. There are also teams in each of the four operating regions the Garda force is divided into. Furthermore, analysts are based within many of the specialist units, including those that investigate drugs and organised crime, sexual crimes and frauds, among a range of other serious offending.

When assistant commissioners – who are in charge of policing in each region – hold monthly meetings with their chief superintendents a Garda analyst is present. They feed information about crime trends in specific areas into the meetings so that policing for the following month, and beyond, can be formulated to meet current demands.

In the case of organised or violently burglaries, for example, the analysts can spot when and where spikes in activity started to emerge. But they also drill down into the particular details of each offence – recorded on the Garda’s Pulse database – to extract much more specific information.

For example, they may be able to link a known suspect or gang to crimes committed outside an area where they usually operate. Without the work of the analyst, Parsons says, different teams of gardaí may not be aware crimes committed in their respective divisions are missed.

The drilling down into records of individual cases also focuses on the modus operandi of a gang or suspect, which helps to identify new and emerging gangs becoming more organised or prolific.

The more general work – on crime trends – has helped inform Operation Thor, which has targeted prolific burglary gangs who travel around the regions carrying out their crimes. Despite recent media coverage, Parsons says burglary numbers remain very low in Ireland, though she says it is important to acknowledge some recent victims of burglary gangs have been left badly injured.

‘Unique job satisfaction’

Analysts also provided the information on which Operation Citizen in Dublin was based. Under that operation frontline Garda resources were increased during the Christmas period to keep central Dublin safe and assuage some unfounded fears that the city had become more dangerous during Covid-19 lockdown periods. The information provided by the analysts identified specific streets and times where trouble, especially assaults, were most common, enabling gardaí to be deployed accordingly.

Parsons says that when the information spotted and analysed by her staff is deployed into a specific crime investigation, and results in a suspect being caught, it is a “massive” result for them.

“That’s the really unique thing about policing, there’s such unique job satisfaction. You’ve helped the team in some way to catch the bad guy and you’ve got the charge over the line, you’ve played that part.”

Parsons says while big data and data analysis is now big business across all sectors there is no single qualification a candidate needs. This has led to a diverse bunch now working for the service including “statisticians, psychologists, social scientists, physicists, biologists” all bringing in their unique takes to the job.

Parsons adds while people “in certain circles” – meaning for-profit organised crime – are generally more aware of how data can be use against them, it is hard for them to escape the net that her analysts are able to cast.

“Even with a phone, there are details of internet traffic and things on there. The world is so connected now, and so much is online, that you have to be totally off-grid for there not to be some information that an investigation team could have.”

Conor Lally

Conor Lally

Conor Lally is Security and Crime Editor of The Irish Times