I agree, taking someone else's life should always be avoided. The only exception I make is in the protection of life. According to Locke it violates natural law to do so. That being said he also points out that by violating that natural law, you forfeit your own protection. Now that is time sensitive. If someone is in the process of killing someone it would be lawful to protect them or yourself by defending yourself up to and including killing them, but if they leave the scene and you track them down and kill them that would not be lawful.

As for Freedom, the definition I like is - The state one is in where no one is forcing their will upon the individual.