Police in the Republic are investigating after a bomb hidden in a vacuum cleaner box was sent to a social worker.
A threatening note was attached to the "highly complex" device, believed to be linked to the respected woman's work.
Sources said gardai and army experts have rarely seen such an elaborate bomb.
A Dublin-based criminal gang has been identified as the chief suspect.
"As part of her work as a senior social worker, this woman has had to interface with criminality as part of her job," a source said.
"What seems to have occurred is that a Dublin-based criminal gang had a deep grudge against this lady because of her diligent work in a particular case."
After the bomb was delivered to the social worker's place of work on November 16, she placed it in the boot of her car and drove for over half an hour to an event attended by a large group of children.
It was when the target arrived at this event that she gave the vacuum cleaner box a further examination. It is understood she noticed wiring and became suspicious.
She then placed it on the ground at the venue's car park. Gardai were contacted and an army bomb disposal team was called to the scene. They examined the device before carrying out a controlled explosion.