S non-immigrants must go through a two step process to apply for a green card.
Step One – File Form I-854, Interagency Alien Witness and Informant Record.
This form is to be completed by the federal or state law enforcement agency or U.S. Attorney’s Office that initially filed for the S non-immigrant status on behalf of the individual.
Evidence that the witness or informant has fulfilled his or her obligations as an S non-immigrant and provided information about all potential grounds of inadmissibility must be included with the completed and signed Form I-854 application. Failure to disclose all grounds of inadmissibility may result in the alien being removed (deported) from the United States. For more information on the grounds of inadmissibility for S visa non-immigrants, please see the Form I-854 instructions.
Step Two – After Form I-854 is approved, file Form I-485, Application to Register Permanent Residence or Adjust Status.
About Adjustment of Status
The Attorney General may adjust the status of S-5 non-immigrants and their family members to that of aliens lawfully admitted for permanent residence (LPRs) if the aliens have supplied information as agreed, and the information has contributed substantially to a successful criminal investigation. The Attorney General likewise may adjust the status of S-6 non-immigrants and their accompanying family members to LPR status if the aliens have — in the sole discretion of the Attorney General — substantially contributed information that led to:
1) The prevention or frustration of an act of terrorism against the U.S, or
2) A successful investigation or prosecution of an individual involved in such an act of terrorism.
The informants also must have received a reward under §36(a) of the State Department Basic Authorization Act of 1956.
In order for an “S” non-immigrant to adjust status, a Form I-854 must be filed on the alien’s behalf by the federal or state law enforcement agency that originally requested the visa. This application must be approved by the Assistant Attorney General in charge of the Criminal Division of the Department of Justice, and the Assistant Secretary of Immigration and Customs Enforcement of the Department of Homeland Security before the alien can file the Form I-854. These LPR adjustments are then counted under the country ceilings of the numerically limited legal immigration system. Upon adjusting status, the non-immigrant will remain deportable, if convicted of a crime involving moral turpitude, for 10 years after the date of adjustment.