The US Government Accountability Office (USGAO), in an Oct. 1998 report entitled "Criminal Aliens - INS' [Immigration and Naturalization Service] Efforts to Remove Imprisoned Aliens Continue to Need Improvement," stated:

“[S]everal major laws were passed between 1986 and 1996 that provided for the initiation of removal proceedings for certain criminal aliens while they were incarcerated, expanded the types of crimes for which aliens could be deported, and sought to facilitate the expeditious removal of those aliens found to be deportable…

Currently, INS [U.S. Immigration and Naturalization Service] may release deportable criminal aliens, including aggravated felons, from custody only if the aliens were lawfully admitted to the United States, or were not lawfully admitted to the United States but the designated country of removal will not accept the aliens, and the aliens satisfy the Attorney General that they will not pose a danger to the safety of other persons or of property and that they are likely to appear for any scheduled proceeding.”

Oct. 1998 - “Criminal Aliens – INS’ Efforts to Remove Imprisoned Aliens Continue to Need Improvement”