Regulus chuckled. "You are... adorable, thinking that you have any power here. I do not need to do anything and I don't need Dumbledore to speak in my defense, because I haven't done anything other than working to stop the Dark Lord, for which I should get a medal."
He got up. "I'll tell you what I'm willing to do. I'll give you time to investigate, while I go back and get more information. I'll also pack my things and get ready to come home. In a few days, I will let my family know that I'm alive. Whether you're ready with your investigation or not, it's really your problem. Whether they come after me, it's really my problem. Hopefully we can help each other, but it's not really a necessity."
Reaching into his robe, he took the vial with the polyjuice. "Now, if you'll excuse me, I must go. I can't have anyone being suspicious."