This topic seems to come up frequently these days. There seems to be much confusion about what neuroscience can and can't do. A recent report from the Royal Society tries to draw some lines. I personally liked David Eagleman's treatment of this topic in Incognito (though the focus was different). I believe we should not care directly about guilt but about how to best establish the future safety of society. The reason to put criminals away is not because they deserve it but because if they are likely to commit another crime, this protects society. "Fixing" criminals so they won't want to commit any more crimes is not really science fiction (was it ever?), considering the role of psychiatric drugs in America today.