Considering the fact that we can't get 100% of non-Muslim Americans to denounce the attacks on 9/11 WITHOUT BLAMING AMERICA FIRST, I think you should have spent about .8 seconds on Google to find your answer.
The problem is partly Islamic and mostly Arabic. Whereas in Judaism and Christianity the right and wrong you commit do not depend on the religion of the receipent, in the ARab culture it is not the case. In essence, a lie to a non-Muslim is not a lie, sexual frivolities (including rape) against a non-Muslim woman is not a frivolity, etc. The loyalties are in decreasing order: to your tribe, to your confederation of tribes (country), to Arabs, and to Muslims. Thus, you should always support a member of the tribe against a member of another (no matter, almost, what your friend did). That is why an Arab will support another Arab against a Turk but a Turk against a Russian, for instance.
The Muslims here were caught in that net. They simply cannot acknowledge before an infidel that a Muslim was wrong.
HAving seen the backlash after few months, they got wiser, and your Googls search may indeed find something (the first few I read were conspicuously abreviated; the ad did not have a date).
I watched it happen without any prejudice. In fact, I fought with those who attacked Islam itself (to the point one poster told me to go back to "my country" and pray to my "moon God"). I was the one to post on FR the reply from Bush to the Turkish Association, primarily because the original letter sent to the White HOuse was so patriotic and so moving.
Yet, I as well as many others noticed the absence of unconditional condemnation from the Arab organizations in this country. They would begin with "Islam is against violence," and before the sentence is over, "... because of American policies in the Middle East."
Do your Googling again.