Against popular beliefs, I feel the GF had nothing to do with it.
I feel this way for a number of reasons. One of those is because of how deceptive DO is during the interrogation- I am instantly drawn to him, knowing he is involved somehow. It would be hard to imagine DO and Diane conspiring on this together! She had nothing to gain from the death and had future plans with RO.
In Diane, I don't detect deception so much as anti-social bitchiness. Her sugar daddy/pay cheque is now gone and she's pissed! Her secret affair has been revealed in the most overt way. Her emotional reaction to all this is logical. She is drawing attention, she's shocked, appalled, in horror... shutting down. The Killer prob wouldn't be comfortable outside the office on the morning after- lurking around, asking questions, trying to enter the building..
During the interrogation-DO never gets angry that he's being accused, that the officer is wasting time, the killer is walking free. Wouldn't any normal person get upset about being accused? or even show upset at finding out your dad was murdered. Especially if the cop didn't tell you right away.
Not if you already reconciled the death in you mind and were at peace with it. Dennis is a person who is trying to "act" innocent. A person trying to prove through endless conversation that he is just not capable of it. Innocent people don't feel a need to do that.
The CBC doc is all about the red herrings. I believe that DO felt he could use Diane as a red herring. I mean... his dad had a cray cray stalker. Thats a score for him! Whenever he speculates during his interrogation about who may have done it- it's either a crackhead or the mistress. This man doesn't know what happened but feels fine speculating who did it....
I think DO did this with an accomplice. Maybe a family member and a hitman. An accomplice brought and removed the murder weapon. And possibly did the actual killing. While DO provided access to the office, ensured his father was there alone, and payed the killer at a later time.
