Ummm.....that's riduculous. Are you trying to convince us that you have no unused and or unopened items in your home and it is therefore expected that no one else would either? I know I have tons of purchases laying in storage bins and drawers that someone bought and still not used. Rope is not a gun, you do not have to register it or report.
OK I'll slow down.
RN paper: The perp took the paper from a pad that was
later found to be among household items. The R's don't deny this. The perp wrote the RN from paper taken from this pad.
Paintbrush: The perp broke off a section of paintbrush
later found to have been among art supplies. The R's don't deny this. The perp improvised a murder weapon from the section taken from this paintbrush.
Cord: The perp cut two lengths of cord from a roll
later not to be found among household items. Nor were any other cut lengths found. The R's deny any knowledge of cord. The perp used the lengths of cord to murder JBR, cut from an unknown roll.
I guess you think two out of three is good enough for RDI accident/coverup scenario. Three out of three would've been a lot better, especially since the cord was part of the murder weapon. Remember that if it was an accident, then
all items needed to have been among household items.
From this point, RDI accident/coverup scenario can't proceed without assumptions that
... the cord was among household items,
... managed to become among household items innocently,
... and without any witnesses.
These assumptions are made without any evidence to say this is so.