You can love anyone. You can avoid hate, and try to understand another person's choices, whether you agree with them or not.
I would say that, even people who have done great evil still have redeeming qualities. It is totally possible to love them, cherish their good points, but out of that love recognize that they cannot function in society without violating others. In that way, a person can fully love them, but still imprison them, stop them from doing bad things.
But practically speaking, we have values. It is hard to still love someone when they have violated those things. And I can hardly blame them.
Could you love someone, and imprison them for life? Look them in the eye, and in all honesty tell them that while you love them, and wish they could be better, that they cannot be a part of society anymore...? This is usually an action that comes from hate or disgust.
Also, if love is truly unconditional, is it really love...?