The LE said this was a targetted murder not a robbery. I would think robbers would have provided more obvious evidence in the house. Even the PI speculated this was a contract killing. I would hesitate to think that a robbery for jewelery (which can usually be traced) and cash (how much cash do you think the would have lying around considering they had staff and a real estate agent with clients coming and going) would take the time the strangle both people with belts and remove the ties that bound them together. JMO
I'm not sure they can know just yet whether anything was stolen/missing from the S home, until family can have a look (even at photos)? That Toronto couple who were killed in Florida in 2013 had only one ring stolen, which supposedly appears to be the motive. (Unless the theft of the ring was proof of a contract completion, and acts as a reason to point LE in the wrong direction?) jmo
"Flournoy said the killings were likely motivated by robbery as Wise's one-of-a-kind wedding band previously valued at $16,000 was the only item taken from the couple's home."
http://www.cbc.ca/news/canada/toronto/dna-profile-florida-murder-suspect-1.3535947