“Alors même que” is not different from “alors que” but expresses an emphasis about events being simultaneous which denotes irony, strangeness or humor.

Another way to emphasize that irony would be

Personne dans la ville ne doutait d’elle, alors qu’elle était justement en train d’éliminer ses ennemis jurés.

This sentence implies that if there was a moment (in the past) to doubt her, it really was while she was killing her ennemies.