BBM:
Returning to my familiar refrain for this case:
"For the love of money is the root of all evil."
That ring looks to have cost a pretty penny.
I don't think there's any way this perp left that ring on her finger.
I don't think it was pawned, either.
There's no way the perp would gift it to someone else.
Because, M$ney.
I see a couple of possibilities:
1) The ring was left behind at the house somewhere SM might plausibly have removed it herself, e.g., on her bedside nightstand, next to the kitchen sink, etc.
2) The perp squirreled it away somewhere for safekeeping.
JMO.