The immediate reaction of all first responders and gardaí to the crash near Athy in Co Kildare will have been, firstly, to secure the scene so that they could work safely within a defined space. The second step will have been to find and attend to any injured persons.
It is a blunt and sad fact of such situations that the dead, once their demise has been determined by paramedics and/or a doctor, are left momentarily in situ, in favour of tending to the injured alive.
However, once the injured have been removed to hospital and the bodies of the less fortunate have been taken to the nearest morgue for autopsy, garda forensic investigators come to the fore at the scene.
Their task will be to help determine what precisely happened - that is, what caused, or was likely to have caused, the crash.
Key to this task is a detailed examination of the crash scene and the vehicles involved. While human behaviour, in the form of drink and drug driving, speeding and general recklessness, is frequently a key factor in crashes, it is not always so.
Differentiating between supposition and assumption, on the one hand, and empirical, evidence-based fact, on the other, is the job of the forensic examiners.
The scene will be measured and photographed - both close up but also from a variety of vantage points, usually related to the apparent direction from which the vehicle, or vehicles, had been travelling at the time of the crash.
A map of the crash scene will be drawn, initially by hand at the scene itself but later transposed digitally according to the precise measurements taken at the time of the initial examination.
This map will show the final stopping positions of the vehicles involved as well as a debris field, which is the area around the crash scene in which smashed and broken parts of the vehicles are strewn. This allows for a thorough search of the scene because, in defining the outer extremities of the crash scene, the entire area is being visually examined simultaneously.
Point of impact
The places where debris is concentrated will also tell gardaí where the point of impact was and can also give an indication as to which vehicle was moving fastest.
The point on the road where the vehicles first impacted on each other is usually obvious due to skid marks, gouging scars on the road surface and the concentration of particular types of debris, such as glass or paint, on the road surface.
Forensic examiners are able to tell much from a detailed study of a crashed vehicle. It is possible, for instance, to know even from a shattered light bulb whether it was working at the time of the crash and whether it was switched on.
It may be possible also to determine the speed at which vehicles were travelling at the moment of impact. Whether seat belts were worn at the moment of impact will be obvious to those who are first upon the scene but belts and buckles will also be checked by the forensic examiners.
Breaks and steering mechanisms will be examined to see whether any mechanical faults were present at the time of the crash and, if so, whether such defects could have contributed to what happened.
Bodies examined
The bodies of those who died will be examined for evidence of use of drugs, legal or illegal, and alcohol in quantities that could have altered behaviour. Other parties to the crash are also likely to be asked to provide samples for similar testing.
All of this information will in due course guide a decision, which will be taken not by gardaí but by the office of the Director of Public Prosecutions, as to whether any criminal charges should be laid against anyone in relation to the crash.
If not, an inquest will be held. This is a judicial, public inquiry in which evidence is given under oath, and in which a coroner and jury seek to establish the “who, when, where and how” of death without apportioning blame specifically.
Juries often add riders to their verdicts, however, which can sometimes indicate, in their view, a level of culpability on the part of either authorities or individuals or both.
