Originally Posted by laudienne

Theoretically {because we have no way to know for sure -- unless we ask JKR herself!}, I personally think this is the case for Lucius too. I have to agree with the majority in that Lucius would have had to have used the Killing Curse, on at least one occasion, to prove his loyalty to Voldemort. I don't know if I see a soft side in him at all .. he is cruel, cold, unforgiving, and honestly evil. I can see him killing for fun, killing to feed his ego and his superiority complex, killing to preserve the "master race" that he believes is the Pureblood. Further, like it was brought up earlier, we see several times that he is bordering on speaking an Unforgivable -- I'm sure there were many times in the past when no distractions came in to stop him from doing so.