Re: Tourist Applying for U-Visa
How he came to be here as long as he is legally admissible isn't an issue. Yes he can apply here while on the VWP.
Of course he has important criteria that needs to be met: that he has been the victim of a qualifying crime (mugged is too generic, it has to be a felonious assault).
He has to have SUBSTANTIAL abuse as a result. Treated and released probably doesn't qualify.
He has to have a information about the crime that justifies him staying to aid in prosecution.