Spouse Visa, spouse cheats and leaves

Hi all,

My brother married his wife in China, and got the visa for her to come to the UK. 3 months into living here, she was cheating, left him, and moved out to an unknown address.

What is her legal status in the UK? Can she still stay here legally? If not, what's the best way to report her?

Thanks,
Jon

Your brother should write to the Home Office advising them that his wife is no longer living with him. That's all he can do. The UKBA may (if they trace her) make moves to terminated her stay, but they often do nothing. She will be unable to apply for ILR as a spouse when the time comes.
Unfortunately this is far from uncommon.