For a crime victim to be eligible for U nonimmigrant status, he/she must obtain law enforcement certification. The Department of Homeland Security (DHS) released a pamphlet “U Visa Immigration Relief for Victims of Certain Crimes: An Overview for Law Enforcement.” Even though the pamphlet is directed at law enforcement personnel, it offers a good overview of the U visa for victims of certain crimes. https://www.dhs.gov/sites/default/files/publications/U-Visa-Immigration-Relief-for-Victims-of-Certain-Crimes.pdf