lets say that someone did something illegal when there 14 but it isnt trialed or found out until the person is over 18 would he or she be trialed as a minor or an adult

I do not research law... but it may depend on the crime.

They'd be trialed as a minor, seeing as the crime occurred when they were a minor. But there are plenty of other factors to consider, like the statute of limitations and the seriousness of the crime, to name a few.

There was a case a while back about a 17-year-old sniper assassin that could not receive the death penalty for the simple fact that he was a minor at the time.

Lessee...it depends.

It depends on the town/county/country where the crime happened, the town/county/country where person is now, what kind of crime it was, whether there were aggravating or mitigating circumstances, whether there's a statute of limitations for that crime, whether there are mandatory minimum sentences for that crime, whether laws have changed regarding that crime since it happened....

I think you get the idea. There's no way for any of us to give you an answer without tons of details AND a lot of law knowledge about all those specifics.

And even for those who do have lots of law knowledge, you'd better make sure they have law knowledge for the place OF THE CRIME. I may have read a lot and seen lots of examples about how it works, but those examples are all from MY city/country. I see you're in Ireland, so who knows all the ways it's different there. It certainly changes from state to state within the US.

Statute of limitations - Wikipedia, the free encyclopedia

I'm no lawyer, but I'm pretty sure that you couldn't be retroactively tried as an adult for a crime you committed as a minor. In the same way, you can't- as far as I know- be sentenced based on laws that have been enacted in the period between the crime and your trial.

Are you saying this is happening to you?