Here's a very interesting article about "parricide"- homicide where a child kills a parent or loved one.
http://www.theforensicexaminer.com/archive/fall08/6/ It's full of great information.
Disclaimer: Great article (thank you!) but way too long for me to read in entirety online. I freely admit skimming over details about particular cases.
Although we don't know for certain the circumstances of Wayne Millard's death, the cited article had one particularly interesting section to me: "Prevention & Protection: Options for Parents & Other Family Members." In the author's view, there are ways of protecting oneself from psychopathic children (after admitting that there is a problem of course!), and we know that at least two of the four ways listed were not met:
1) "important documents or items, such as any financially related documents, wallets, and purses, must not under any circumstances be accessible to the child" - We have photographic evidence that the father's credit cards were easily accessible.
2) "computer access codes must remain within the province of the parents..." - From
today's article in the National Post, "according to SG, the brother of Wayne’s girlfriend at the time,EG, Wayne didn’t use computers or email."
3) "parents should make sure that the child does not have a key to their home..." - We know that Dell lived at home.
4) "communication between the family and adult child should be handled with care, especially if such communications could be interpreted by the adult child as somehow threatening." - unknown
It will be interesting if additional information about communications between parents and child do become known. As ever, MOO.