Throughout the 1990s, Los Angeles (L.A.) County officials grew increasingly concerned about the negative impact of criminally involved aliens on local public safety and criminal justice resources. Of particular concern was that subgroup of criminal aliens who had been previously deported from the United States and later rearrested for new criminal activity in L.A. County. In response, a multi-agency partnership was formed called High Intensity Criminal Alien Apprehension and Prosecution (HI-CAAP). The goals of the HI-CAAP partnership are to increase the identification and federal prosecution of previously deported criminal aliens. This report is an assessment of the partnership’s progress toward implementation of these goals. The findings are that considerable progress has been made in identification of previously deported criminal aliens, including increased ability to make a fingerprint-based identification; improved working relationships with the Bureau of Immigration and Customs Enforcement’s Law Enforcement Support Center, and progress toward implementation of an automated immigration detainer process. There also appears to have been progress toward the goal of increased federal prosecution of HI-CAAP aliens. Despite no increase in resources, the United States Attorney Office has been actively seeking methods, such as the adoption of the Fast Track program, to increase the number of federal prosecutions of criminal aliens. The issues raised in this report may serve as informative background for federal policymakers and local jurisdictions seeking to address criminal aliens. While they are not easily developed or maintained, such partnerships may hold great promise for addressing the multijurisdictional problem of previously deported criminal aliens.