The usual result when someone commits a crime in the U.S. and is a temporary visitor (most likely with a visa or on the Visa Waiver Program) is that the person is placed in deportation proceedings. After a hearing before an immigration court judge, the person may, if his or her crime constitutes a ground of deportability, be removed from the United States. But there’s a separate, lesser-known potential consequence to committing a crime in the U.S.: revocation of the person's visa, in some cases by the U.S. consulate that issued it in the first place.
When a visa is revoked, it is simply canceled, on the grounds that its holder is no longer, or never was, eligible for it. That doesn’t necessarily mean that you have to leave the U.S. in short order. The consulate or State Department Office that makes the revocation decision will give you details (or you may be separately placed into removal proceedings).
It also means that you cannot use the visa to reenter the United States. If you wish to reenter the U.S., you will first have to apply for another visa or qualify for another basis upon which to do so. Depending on the nature of your crime, however, you may be inadmissible (and thus ineligible for any visa or U.S. entry) for a number of years.
The U.S. consulate that issued your visa has the power to revoke it in only one circumstance after you have left for or arrived in the U.S.: a finding that you have been arrested for or convicted of driving while under the influence of drugs or alcohol (a DUI). (See the Foreign Affairs Manual at 9 FAM 403.11-5(B)(U), Prudential Revocations.)
The basis for this exception is that the person was inadmissible upon entry to the U.S., under § 212(a)(1)(A) of the Immigration and Nationality Act, which lists health-related grounds of inadmissibility. The applicable one concerns physical or mental disorders with associated harmful behavior. Because of the seriousness with which DOS regards DUIs, it does not want to take the chance that a person with a long-term visa will face no consequences, and be able to return to the U.S. over and over again, for a number of years.
Another office of the U.S. Department of State (DOS) is empowered to issue revocations for other crimes: It’s called the Visa Office of Screening, Analysis, and Coordination (CA/VO/SAC) This office may receive information about arrests or crimes, or actual revocation requests, from partner U.S. agencies or overseas consular posts.
It will review these and decide (after several layers of review) whether the visa holder’s continued eligibility for the visa has been called into question and whether the visa should therefore be prudentially revoked. A mere suspicion of ineligibility may be enough; this office’s decision does not require an actual conviction or the person’s admission to having committed a criminal act, much less notice to the visa holder or a hearing.
Fortunately, this lack of a full hearing or a final judgment means that the door is left open for the person to receive a fuller consideration from a consular officer upon reapplying for a U.S. visa.
U.S. Citizenship and Immigration Services (USCIS) may also play a role here, particularly if you have a pending application (such as for an extension or change of status before it). If the agency receives information regarding a person's pending criminal charges, it may send out a Request for Evidence (RFE) or request an interview. This may actually be a good thing for the applicant, offering an opportunity to rebut or otherwise deal with the negative information.
After a decision has been made to revoke your visa, the Visa Office or U.S. consulate would send you a letter explaining the decision and what it means for you. It will explain that the visa is not valid for future travel to the U.S., and ask you to present your current visa to a U.S. consulate for physical cancellation after leaving the United States.