More confusion about 疑う


> 彼は彼女がオオカミではないかと疑った。  
>  He suspected that she was a wolf. (given translation)

I have read this [related
post](https://japanese.stackexchange.com/a/87181/7944) but I still struggle to
understand when 疑う means 'doubt' and when it means 'suspect'. My feeling is
that I should interpret it as 'doubt' unless there is a compelling reason to
do otherwise. Would that be fair? Can the compelling reasons be easily listed?

In this example sentence we seem to be doubting a negative statement;
literally "I doubt that she is not a wolf". This would be a truly bizarre
thing to say in English unless someone beforehand had said something like
"That woman claims that she is not a wolf". Whereas, saying "I suspect she is
a wolf" would not require any previous context in order to sound natural.

Is the above Japanese sentence natural without prior context? If Xと疑う means "I
doubt X" then is (negated X)と疑う the natural way to express "I suspect X". If
not, what would be a natural way?

