The best thing you can do is hire an immigration attorney with some criminal experience who can access your friend's CADOJ and FBI records. Depending on the Visa, it may still be within the discretion of the border officials to decide whether or not to let your friend enter the U.S.
I agree. If his visa has already been cancelled he will need to re-apply at the consulate and demonstrate curernt eligibility.
Lynne R. Feldman, Attorney at Law
Concentrating in Immigration and Nationality Law
2221 Camino Del Rio South, Suite 201
San Diego, CA 92108
phone: (619) 299-9600, facsimile: (619) 923-3277
Formerly Adjunct Professor -- Immigration law
University of Illinois College of Law