I noticed a headline regarding an Israeli release of convicted murderer Marwan Bargouti in exchange for Jonathan Pollard, Shlita, and Assam Assam, Israeli prisoner of Egypt. Would this be possible according to Torah Law? Why or why not?

Releasing a murderer in exchange for another person, live or dead, is forbidden: A. He needs to receive his punishment. B. When he is released he will continue to kill other people, or else others will learn from his case that punishment on murdering isn't so harsh and they will go on murdering. C. Enemies will continue taking prisoners in order to exchange them for their murderers, knowing that we are willing to negotiate. Rabbi Ro'i Margalit