Re: "Should you do anything to help them?"
Excellent analogy!
The answer to your rhetorical question is *not*:
See if you can talk some of your neighbors into breaking in to his home and killing him. When you find that only one or two are willing and the rest think you are crazy, you go ahead with your plan anyway.
And the answer to your rhetorical question is:
Call the cops. Then they should do an investigation to find if a law has been broken. If evidence is found then the courts will decide what the proper punishment should be (maybe removing by force the leader of the family; maybe not).