Where have I said that I like the idea of a possible release? I obviously would NOT be happy that someone with the intent to harm me based on the country I live in was free and surrounded by people of like mind.
My point was that it's going to be pretty obvious that a prisoner freshly released is going to harbor resentment towards the country that imprisoned them, which would be compounded by poor treatment/lack of a reason for detainment. Does this fact make it Okay to keep people in jail without cause? No. I'm simply refusing to let what I believe in (innocent until proven guilty, torture is bad, I wouldn't want to be in that person's shoes, etc) be destroyed by fear-mongering.
And how can you say one killer is more dangerous than another? Especially if they are all in jail together... behind bars... under heavy security?