Social media now a valuable source of evidence in criminal trials

The most obvious uses of the tool are in defence cases but recently prosecutors are also getting in on the act

In recent years Facebook and its equivalents have become an invaluable source for lawyers. Photograph: Niall Carson/PA Wire

In recent years Facebook and its equivalents have become an invaluable source for lawyers. Photograph: Niall Carson/PA Wire


“You appear to be straddling a naked man in this photo,” the barrister said as he held up a screen grab with an unmistakable blue border. “Is this typical behaviour of a woman who lost her confidence because she was raped just a few months previously?”

The young woman sitting in the witness box in the Central Criminal Court appeared nervous as she replied that she was entitled to have a good time and, besides, the man wasn’t completely naked. The senior counsel appeared pleased with the point he had made and moved onto another area.

This exchange occurred during the cross-examination of a woman who was raped as she slept in her bed (the accused was later convicted). The picture came from her Facebook page.

It may be a morally questionable line of defence to some, but it is also a prime example of the increasing use of social media as a defence tool in criminal trials. In recent years Facebook and its equivalents have become an invaluable source for lawyers who are coming to realise that a few indiscreet photos or ill-advised status updates can often be enough to put some doubt into a jury’s mind about a witness’s evidence.

“Facebook evidence inevitably becomes involved in a large number of crimes or other legal matters,” says Ross Donnelly, a digital forensic investigator with the UK-based Keith Boer Consultants.

Donnelly specialises in analysing social media for media clients and business is booming, both here and in the UK: “Inquiries regarding Facebook evidence have skyrocketed in recent years; with over a billion users worldwide so it’s no surprise.”

Police forces, including the gardaí, have invested heavily in digital forensics but Donnelly believes so-called Facebook evidence is “a much more specialised niche” which requires outside expertise.

“Often, Facebook evidence is captured by frontline gardaí or in-house IT departments, who may miss vital evidence as they don’t have a forensic background.”

This is where his company comes in: “It can be a case of just advising the solicitors and barristers, who may not use Facebook themselves. Other tasks include producing Facebook content in an auditable fashion, examining Facebook logs for evidence in relation to a specific allegation, or a full forensic examination of a computer.

“This could be to recover deleted Facebook content, or to identify the user of a computer at the time another crime was committed, for example the downloading of indecent images of children.”

Most of Donnelly’s clients are on the defence side, as police forces will usually rely on their own in-house specialists. His most common jobs are the “I didn’t send that message” cases which involve examining Facebook logs for evidence of someone else accessing an accused’s account to send illegal messages.

State of mind

He is also occasionally enlistled to challenge prosecution evidence about an accused’s state of mind. He cites one example of a man who was charged with murder by strangulation. During the trial the prosecution presented evidence that the accused had twice googled the term “garrotted” before the alleged murder.

However, when his computer was analysed, the first search was found to have never taken place. As for the second search, investigators were able to produce an innocent explanation by examining the man’s Facebook chat log. They discovered that he had searched for the word immediately before using it in “friendly banter” with a pal on Facebook’s chat function.

The defence was able to show the search was unrelated to the death and was “a natural progression from checking the spelling and meaning, to posting the comment”.

Donnelly says that searching through complainants’ Facebook photos for holes in their testimony is a less common activity, as an investigator’s work must be based on specific instructions from the client.

They cannot just trawl through an account looking for something that could help as such “fishing exercises” are not looked on favourably by the courts.

However, Donnelly is happy to help if a client asks him to check for evidence that a complainant had been out socialising on a particular night after an alleged attack.

Investigators also have to make sure they cannot be accused of “hacking” accounts. That means they mostly deal in public information; the side of Facebook that can be accessed by anyone.

“We don’t have any special tricks for accessing users’ private Facebook information,” Donnelly says. “Unless the complainant gives their permission to access their account directly, only the information publically available to any user can be accessed.” It is open for investigators to obtain a court order to compel Facebook to hand over private data, but it is a difficult process. Donnelly says Facebook is renowned for being reluctant to hand over information and will often reject orders it considers “overly broad”. It is usually easier to simply get disclosure of the evidence after the gardaí obtain it themselves as the social media giant seems to be more helpful when dealing directly with the State rather than the defence.

Social media sites such as Facebook are simply another means of communicating so it is no surprise they have become such a valuable source of evidence in criminal trials. However, the public and permanent nature of the communication makes it much more useful in court than a phone conversation.


As Donnelly points out, the most obvious uses are in defence cases but prosecutors are also getting in on the act. A survey in the United States last year of 500 law enforcement agencies found that more than 80 per cent used social media in criminal investigations.

There are no equivalent figures for Ireland but there is evidence that prosecutors here are also becoming more comfortable with using social media as a tool.

In 2011 gardaí used an accused’s Facebook friends list to show he had closer links with alleged kidnappers than he initially let on. He was later jailed for sourcing a vehicle for the alleged kidnappers.

And a few months ago a court heard how a resourceful garda used his own Facebook friends list to track down a distant acquaintance who had assaulted him during 2012’s infamous Swedish House Mafia Concert in the Phoenix Park.

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