What gave Vera confidence to weave her story about the tragedy in "The Open Window"?

If
theVera intends to tell Framton Nuttel had actually happened, it would certainly have been known
about and talked of all over the county. She has to establish that Framton is a complete
stranger to the area; otherwise, he might wonder why he never heard anything about the incident.
If Vera's aunt had been driven insane by the gruesome tragedy, that would also be the talk of
the families for years. Vera first has to establish that Framton knows nothing of
any...