There isn't conclusive evidence that she's stealing from MIL and the nephew. True, items disappeared, but chances are, if this person's criminal past hadn't become known to the OP, she never would have thought to accuse her. Now that she suspects that SIL has a larceny conviction, it is tempting to "point the finger" at this person, but you simply can't based on suspicion! Innocent until proven guilty and all that. Maybe the money was lost. Maybe the Nintendo DS did get thrown out. Maybe someone else took them. Who knows? Baseless suspicion wouldn't exactly hold up in a court of law. A first year law student would be able to win that case!![]()
Regardless, the best predictor of future behavior is past behavior. And the SIL was suspected of stealing from MIL at the time of the incident, but the OP and her husband thought she couldn't have done it because she was "so sweet." I wouldn't run around saying "SIL is a thief!" but I would certainly not trust her.