Ok, you don´t care, but I would like to know that my country has supervision and control of psychopaths or lock them in forever (In Sweden, a lifetime sentence means forever if the inmates cannot live in society as normal people). Dreaming can always be done, what if there was a dimension door and we could push in all the undesirable? You want him to disappear from society is the same resonance that SD (Sweden Democrats) emphasizes, namely that all Muslims should leave the country. It is unrealistic and we will not come up with a logical solution.
To be honest i doubt an actual "solution" exist, because
A modern western politic is weak af versus true criminals and in particular people that come from not-west (as they're used to much harsher law, for less gain and less nice life)
and
B as said the EU does'nt give any fucks about your or mine society being ruined. If anything they're probably bothered that as reply to that, some citiziens (example italians) are against their beautiful enginered invasion plan.
In fact that result in (likely) EU sabotage of said government and support of a puppet one not voted by these
Take these two, and imagine how much i consider realistic a 2019 TRUE tackle on these enemies of our continent (speaking of criminal-immigrants, NOT immigrants)
A "simple" (and yet someway impossible) solution will be permanent expulsion for who commit crimes, simple as that: you're allowed to stay, but if you break host nation law you instant lose that right
There could be even more levels to that, like tackle also on who cover them, but if above is already impossible, this second part will be straight fantasy in current climate
Reality is modern fake politic will not give a true solution
Maybe something will be done at some point, mostly to keep calm the sheep with the illusion they're taking european problems as truly important (lol) and avoid the risk that despite theyr propaganda/censorship/sabotages, anti-EU/anti-nice invasion plan sentiment can rise, giving some nations sovranist governments.
They may even support and make win controlled right-wing movements (Merkel is "right" on paper, and at same time biggest EU player) and do some irrelevant things, but they will not "fix" the invasion... They wanted it, sponsored it and greatly helped it
When Koln's NYE events happened, 1000+ north african immigrants sexually assaulting any german girl/woman they can get hands on, "right wing" Merkel was in charge and authorities tried to cover it
You want a solution, you will not get one
A huge piece of crap has been dropped in your dinner plate, and they will not change it with a new one.
A bit bothered by your complaints they will squeeze some spicy sauce over it to cover the taste, but you will still have to eat the crap. And tomorrow same restaurant, because no other restaurant will be allowed to stay open
I mentioned EU because focus on Sweden is short sight, different nations are facing same offensive with different faces