Writeacher, where shall I "who"instead of which" in the sentence below? Thank you.

1) In all revenge tragedies a sexual or violent crime is committed against a family member of the hero, which (stands for the "crime") for various reasons cannot be punished; so even though the hero seeks revenge for this crime, he usually goes through a period of doubt which (a period of doubts) will involve complex planning.

The verb "punish" is not used for crimes, but for people. People are punished ... or not ... for their crimes.

This makes sense:

In all revenge tragedies, a sexual or violent crime is committed against a hero's family member, who cannot be punished for various reasons; so even though the hero seeks revenge for this crime, he usually goes through a period of doubt which will involve complex planning.

Modifiers (adjective/adverbial clauses, participial phrases, adjectives, adverbs, etc.) need to be placed as close as possible (preferably right next to) whatever it's modifying or referring to.
http://grammar.ccc.commnet.edu/grammar/modifiers.htm#misplaced
Read about all of them -- misplaced, dangling ...

I rarely had this problem when I was studying and writing in Latin -- all the cases and number and gender endings took care of identifying the antecedent clearly. However, English doesn't have all those endings, so word order has to solve the problem of misplaced/dangling modifiers!