Glad to this thread back up and running. There have been some old, high profile cases solved recently and I believe it could happen on this one.
If there is anything to the rumor that this was some sort of a hit on only one of the women, this is something to consider:
The only people who knew Stacy would be there were relatives of hers. She can be ruled out as the target. Susie usually spent the night there but was not expected to that night. Anyone who was close to either Suzie or Sherrill would have known she would not be expected to be there that night; graduation night was a big deal in the Streeter household. Would someone intent on killing Sherrill and expecting her to be there alone, gone ahead with those plans when there were three cars in the driveway including one the perpetrator probably did not recognize (meaning they would not know how many were there or even what sex the unknown were)?
If this "hit" rumor/theory/known fact is correct Suzie was probably the target and the perp probably waited until Suzie. The lack of any sign of forced entry and the "crack" in Suzie's Venetian blinds suggest that Suzie admitted the perpetrator to the house.
Whatever Sherrill's financial history, she was able to secure a mortgage on her house. She couldn't have been having too much trouble. On the other hand, there is no evidence she was living beyond her means. There is reason to be.ieve she had any kind of illegal income.