The tragic events in Charleville almost defy explanation. It is difficult to fathom how circumstances arise whereby a young man would take the lives of his brothers before ending his own.
While rare, such events occur with sufficient regularity to allow tentative conclusions about trends and patterns.
Research in the United States and a number of European countries indicates that lethal violence within families takes a variety of forms.
Most common is the killing of an intimate partner; often against a background of long-term abuse. Next is when parents kill their children, known as filicide, while parental infanticide involves a parent killing a child under a year old.
Parricide is when a child kills a parent (or close relative) and siblicide is where one brother or sister kills another.
It is not uncommon for intimate-partner homicide and filicide to be followed by suicide. One study found that half of all intimate partner killings involving a firearm were followed by suicide.
US figures
But suicide is unusual after parricide or siblicide. Siblicide is one of the rarest types of family homicide. A recent review in the US found that of 14,000 homicides recorded in a given year, just over 100 were siblicides.
We know a little about the characteristics of those involved. The perpetrators are usually adult males. The violence is often rooted in unresolved conflicts and unrelieved stresses exacerbated by drug and alcohol misuse. The spark is usually an argument. There is a single offender and a single victim who tend to be close in age. Firearms are typically the weapons used.
The great majority of victims are male, with the rarest combination involving sisters killing sisters. The victims tend to be adults.
So the Charleville case appears unusual in several respects: the perpetrator took his own life, there was more than one victim, the victims were not adults, and there was a significant age difference.
What it has in common with other siblicides is that, as is so often true when it comes to lethal violence, everyone involved was male.
Such awful events prompt an outpouring of community sorrow and raise obvious questions about prevention.
People want to be reassured that every step will be taken to ensure that such grief will not be visited on another family. Unfortunately, no guarantees are possible. Siblicide occurs so rarely that prediction is a highly imprecise exercise.
Ian O’Donnell is professor of criminology at University College Dublin
Samaritans is available round-the-clock on 116 123 or email jo@samaritans.org