The S visa is available to those who have critical reliable information regarding a criminal organization and who are willing to supply or has supplied such information to enforcement authorities or court and the Attorney General determines the presence of such individual(s) in the U.S. is essential to the success of an authorized criminal investigation or prosecution.
Form I-854 (there is no filing fee) is filed by federal or state law enforcement agency along with 2 passport style photographs of the qualifying applicant and evidence of his/her cooperation; the need for his/her presence; grounds of inadmissibility and factors warranting favorable exercise of discretion.