Answer to this question is provided in another thread. I'm quoting here the person who gave this answer:
-- "À cause de is used when it is [because of] a noun, parce que is used when there is [because] some sentence (verb involved):
À cause de ton serpent - Because of [your snake] - your snake is a noun. Parce que ton serpent a mangé tout le fromage - Because [your snake ate all the cheese]
À cause de ma faim - Because of [my hunger]. Parce que j'ai faim! - Because [I am hungry]!" --
"caused by" should be a valid translation, at least in cases as "i have a headache - caused by whom?" (j'ai une migraine - à cause de qui?), but there are other cases when "because of" is more suitable "I am unemployed - because of whom?" (je suis au chomage - à cause de qui?)
It's used colloquially but isn't grammatically correct. If you can substitute the word "him" or "her" in place of "who/whom" it should be "whom". If you would need to use "he" or "she" then it is "who"
"For whom does the bell toll?" "[It tolls] for him"
"Who goes there?" "She [does]"
I think the shift from colloquial to standard began a good while ago and "who" is certainly understood and accepted in both speech and writing these days. In fact, I would dare say using "whom" would count as marked language, standing out when in use (not as an error, simply as a somewhat outdated form).
"à cause de" means "because of" and it's often used for negative situations/consequences. However, it doesn't necessarily imply "fault". http://french.about.com/od/vocabulary/a/a-cause-de.htm