Suspects 1 and 2: Mews and Quigley

"Mon dieu Mews!  You can't possibly expect me to believe that after all this time you are the culprit.  Tell me you're just being thorough Mews," Quigley said looking anxious.

"I am being thorough and fair.  I do live in the building.  Dogs are my natural enemy.  There is no reason why I should be presumed innocent just because I am the sleuth."

"Okay, Mews, and I suppose I, as your sidekick, cannot be completely ruled out as well," Quigley said looking chagrined.

"That's right Quigley.  A detective, as you know, ought to deduce in a systematic manner as a scientist would.  That is why you and I cannot be completely ruled out although I know that I didn't do it."

"And I know that I didn't do it!"  Quigley shouted.

"But I don't know for sure that you didn't do it," Mews said.

"And I don't know for sure, Mews, that you did not do it!"  Quigley looked confused.  "Goodness, my head is spinning Mews.  I think I need a strong cup of tea."

"Yes, I agree Quigs.  And after tea we'll get straight to the next suspect who is neither you nor I."

"Thank goodness Mews.  I think I was starting to sweat.  Metaphorically, of course," Quigley said with a knowing nod.