Fraud?

The big picture:  Hire an attorney with experience in immigration fraud cases -- specifically the type of fraud you're targeting. 

• Immigration attorneys often don't want to take such cases since any precedents or successful case law will hurt their current and future clients. 
• Research criminal, family law and other types of attorneys that have represented similar cases in court. This will involve legal research. 
• One exception is CodiasLaw.com, the only law firm specializing in immigration fraud issues. 
• If you were falsely accused of a crime for a U visa, T visa or a VAWA/domestic-violence green card, research a defense attorney with a history of similar cases. Some defense lawyers have developed expertise in these areas since many Americans have faced false abuse or crime charges for the benefit of a green card. (A single crime accusation can "clean up" the illegal or temporary immigration status for an entire family. Therefore, there's an incentive to commit fraud as other legal immigration avenues close.) 
• Large cities with sizable immigration populations are usually a good place to start in researching qualified lawyers to protect against false allegations for immigration benefits. Even farm areas have attorneys that develop similar expertise. 
• Some public defenders have also developed an expertise in these areas since they've had to represent falsely accused Americans and noticed similar patterns of alleged abuse in a community that are far too similar to be realistic. (Many have contacted me over the years when trying to understand why the details of local cases looked almost exactly alike -- with different victims and different perpetrators. 

In short, do your research!