I think it is a good idea to question that early morning call that places Bob in the house. why not open it up? If we throw out all of the receipts, then we have a heated family meeting when people report that they last saw him alive. That is the last place everyone seems to agree on. They last saw Bob alive at the family meeting.
I will say this-I am prejudiced towards the timeline created by JuM that starts 28 hours after her post.
Because that puts her husband in the house and therefore he must have seen or heard something.
I am on Team Oriah though-what if we throw it all out?
I have no proof for the following other than that allegation that a call that Bob answered was made by a non-family member at 10 am.
Here's my speculation: I don't think we are dealing with a family with the competence to hire a hit man, who would have done the job properly and not left the family open to suspicion like this (when you need a job done with expertise, call in the professionals... it's what the Mafia does).
I think whoever did this was motivated by money and perhaps overtly or covertly egged on by one or more other family members. This person was not an expert but someone who had been thinking for a while "geeze, the old man just won't give up and die... maybe I could just help him disappear and our troubles would disappear with him."
Then the family meeting where Bob probably reminded his descendants that the money was his to do with as he pleased and his pleasure consisted in marrying a new wife and adding her to his accounts. If it had been me, I would have added "and I fully intend to spend it all and die with a dine left for the lot of you to fight over." Bob may have been more diplomatic than I would be.
Killing Bob would be unthinkable at the family meeting, too many witnesses. Too obvious.
Besides, the one who did this is not a professional. I think this person needed some time to think it over and wind themselves up to the point where they could actually do the deed they had been daydreaming on for a while.
And that is why I think Bob really was still alive at 10 am. And why the killer chose to make Bob disappear rather than try to set it up as a home invasion robbery gone wrong.
Besides, the person who did it probably realised the daughters wanted their mother's jewellery and would not willingly sacrifice it to make a robbery look realistic.