QMOP.
Elaborating on this general theory, it may not have been a delusional stalker at all if the Google searches of SG's salary and NG's home were real and were done by the suspect. I could also see a relatively local white collar suspect, or more apt a local suspect who leveraged heavily and lived a 'wannabe' white collar lifestyle, planning and executing the heist with solely a financial goal and his lifestyle continuity in mind. I hope LE is considering this angle if they don't already have a motive and/or someone in mind. After all, there is an obvious level of intelligence and sophistication in the planning and commission of this crime, but with a suspect who perhaps wouldn't account for all variables in its commission. Namely, that a 84 year old lady might have a pacemaker and might have medications she would need to survive his plan long enough to return her unharmed.
Another 'desperation' motive to consider, but with less selfish motives, would be a man with a sick/dying spouse/child who committed the act in much the same way and with much the same motive (financial) and much the same deficiencies in terms of victim planning, in order to have the funds to pay for X or Y or Z treatment, etc. I would be looking at any of these situations locally as well if they haven't already honed in on motive/suspect.
Reason I say suspect would likely be relatively local in these situations is because SG and NG would be famous enough locally to give the impression of vast wealth. Probably top of the food chain in Tucson, in other words. Otherwise a suspect would probably choose someone else somewhere else.
ETA - Not 5 million, not 10 million, not 20 million, but 6 million. That's pretty specific and seemingly with an intention not to bankrupt SG/NG by asking for the moon. Did he calculate what he needed?
JMO.
