Rapped Women in Islam

An American friend asked me yesterday about women who are raped in Muslim countries and then get stoned to death. My eyebrows went up!! Without thinking I told her, "NO WAY". Then after some little thinking i said, , "Maybe, this happens if a woman claims being raped but can't prove it, so this means she had performed adultery - the punishment of which is stoning to death". Could this be true! That's how several online accounts report was the case in some muslim countries like Pakistan, Sudan, Nigeria, here is one. Despite the fact that the sentences have never been executed, this can't be true implementation of Islamic Lay . If it is, what is a rapped woman expected to do??? Just say she's raped and she can't prove who rapped her???