"This land needs badly that very soon crimes will be investigated by the police and punished by the courts and by noone else."

The historic problem- why the IRA exists at all, and why people have allowed the IRA to police their areas- is that the police and courts in Northern Ireland, as well as the whole system of government there, have been part of the problem- biased, sectarian, unjust, violent.

The (shortish term) root of the problem was the deliberate creation of the sectarian state in 1921. That state had, and still has, a built in majority- but just a bare majority- of support, and used its hegemony to promote sectarian divisions, the better to hold its own power.

Any solution MUST end that situation. You can't blame people for not acquiescing to permanent second-class status. That the protest developed into violence was entirely the fault of the legally established powers, and was quite possibly intended.

The IRA are murderous and destructive, and tyrranise the areas they control- but those inhabitants have little confidence that removal of their 'protection' would lead to improvement.