RebYidd:
Come now. You would ask the neighbor if they are being abused? Really? And you would expect the answer to be factually accurate? How many victims of abuse are frightened to death to disclose that information? How many tolerate and suffer for long periods of time before they report anything to anyone?
Review the literature on domestic violence. Let me share a few observations that were reported in the several articles and books written by and for the frum community. Women who are being beaten often hide the abuse out of shame. Many have marks from the injuries, bruises, etc. However, the men are diligent in hitting them where there will not be much exposure, and no one will know. It is not uncommon to find the first alert by the matrons in the mikva who get to see these injuries, while the victims still avoid acknowledging it or seeking help.
The idea of just marching over to ask is close to perfectly ineffective. You need another strategy to make the failure to call police not a clear violation of לא תעמוד על דם רעך.