1) GBC was involved in quite a tangled web, relating to financial and extra-marital issues, and had reached a point where he could no longer live with the pressure;
2) As a result of the intense pressure, GBC found himself wanting to ease the burden and, unfortunately, removing ABC permanently from his life was his best option;
3) Even if ABC's death was not premeditated, GBC had already planned some kind of "escape" from his, at the time, current life situation. ABC, too, would have been feeling the tides of change and, in her own way, determining her new path in life, minus GBC;
4) If ABC's death was, indeed, premeditated, GBC would have had at least one, or two, people close to him, whom he would have spoken to about his plans. IMO, this would have been his mistress, his father, or both;
5) Since the beginning, I have had very negative feelings about Senior BC. I know, I know... They're only feelings. However, I have not been able to shake these feelings of Senior BC being "in the know" and, either directly or indirectly, having involvement in ABC's death and subsequent removal/disposal of her body;
6) GBC's sister has her suspicions, but has not had the courage to fully explore these. As blood is thicker than water, GBC's sister's loyalties are with her immediate family. However, if one or two of her family members are eventually determined to have been involved in ABC's death, I suspect that GBC's sister will come clean with her suspicions and distance herself from her family;
7) In attempting to preserve the family's high profile, clean-cut image (and maybe not so well with the now infamous "Granny Pash"), Senior Mrs BC is also burying her suspicions. In saying that, Senior Mrs BC potentially knows most of the details of what happened to ABC, but wants to protect her husband's and son's reputations until such time she can no longer do this and the full force of the law takes this from her hands.
So... In summary, GBC was the main perpetrator, Senior BC assisted during the immediate aftermath, an individual close to GBC also has a level of involvement and GBC's mother and sister are both going through a period of supressing suspicion (or knowledge of the crime) and supporting their family to, in their hope, maintain their family image. IMO. :moo: