You completely lack understanding of how young immigrants usually quickly adopt the culture of the host country. Maybe you live in a part of Ireland where you don't know such youth.Culturally Irish? What exactly is that? Does this culture offer some legal protections or form the basis of a legal defence?
Do you know the person or people involved? Your staunch defence and support for someone who "committed a serious crime", noted not defined in the OP would suggest you do.
The Irish taxpayer should fund the education, healthcare etc of someone in the country illegally, then fund their prison sentence and god knows what upon emergence from prison? Am i missing something?