This is the accessible text file for GAO report number GAO-05-646R entitled 'Information on Certain Illegal Aliens Arrested in the United States' which was released on May 9, 2005. This text file was formatted by the U.S. Government Accountability Office (GAO) to be accessible to users with visual impairments, as part of a longer term project to improve GAO products' accessibility. Every attempt has been made to maintain the structural and data integrity of the original printed product. Accessibility features, such as text descriptions of tables, consecutively numbered footnotes placed at the end of the file, and the text of agency comment letters, are provided but may not exactly duplicate the presentation or format of the printed version. The portable document format (PDF) file is an exact electronic replica of the printed version. We welcome your feedback. Please E-mail your comments regarding the contents or accessibility features of this document to Webmaster@gao.gov. This is a work of the U.S. government and is not subject to copyright protection in the United States. It may be reproduced and distributed in its entirety without further permission from GAO. Because this work may contain copyrighted images or other material, permission from the copyright holder may be necessary if you wish to reproduce this material separately. United States Government Accountability Office: Washington, DC 20548: May 9, 2005: The Honorable John N. Hostettler: Chairman, Subcommittee on Immigration, Border Security, and Claims: Committee on the Judiciary: House of Representatives: The Honorable Steve King: House of Representatives: The Honorable Melissa Hart: House of Representatives: Subject: Information on Certain Illegal Aliens Arrested in the United States: The former Immigration and Naturalization Service estimated that as of January 2000 the total unauthorized immigrant population residing in the United States was 7 million.[Footnote 1] This total includes those who entered the United States illegally and those who entered legally but overstayed their authorized period of stay. A more recent study estimated that there were about 10 million illegal aliens living in the United States as of March 2005.[Footnote 2] The study estimated that nearly 700,000 aliens entered the United States illegally or overstayed their authorized period of stay each year between 2000 and 2004. Some illegal aliens in the United States have been arrested and incarcerated in federal and state prisons and local jails, adding to already overcrowded prisons and jails. On April 7, 2005, we issued a report on criminal aliens[Footnote 3] that were incarcerated in federal and state prisons and local jails.[Footnote 4] Our report contained information on the number of criminal aliens incarcerated, their country of citizenship or country of birth, and the cost to incarcerate them. You also requested that we provide information on the criminal history of aliens incarcerated in federal and state prisons or local jails who had entered the country illegally. For a population of aliens that entered the country illegally and were incarcerated in federal or state prisons or local jails, this report addresses the following questions: * How many times have they been arrested? * How many and what type of criminal offenses have they been arrested for? * What states were they arrested in? To obtain information to answer these objectives, we identified a population of 55,322 aliens that the U.S. Immigration and Customs Enforcement (ICE) in the Department of Homeland Security determined, based upon information in its immigration databases, had entered the country illegally and were still illegally in the country at the time of their incarceration in federal or state prison or local jail during fiscal year 2003. We then analyzed selected data contained in the criminal history record, commonly referred to as the rap sheet, of these illegal aliens maintained within the Federal Bureau of Investigation's (FBI) Integrated Automated Fingerprint Identification System (IAFIS).[Footnote 5] To assess the reliability of immigration databases used to make the determination about an alien's legal status, we discussed internal control processes for ensuring data quality with responsible ICE staff and found the data to be reliable for purposes of this report. To assess the reliability of IAFIS data, we discussed the data collection methods and internal control processes for ensuring data quality with responsible FBI staff and reviewed relevant policies and procedures. IAFIS may not contain all of the arrests for the illegal aliens in our study population since seven states report only their first arrest to the FBI. Subsequent arrest data is available only from the state's criminal history record system. While the magnitude of any undercount is unknown, we found that the data we used for our analyses were sufficiently reliable for the purposes of this report. Several things should be noted regarding our analysis. First, an arrest does not necessarily result in a prosecution or a conviction. Second, our analysis is limited to the aliens that ICE determined to have entered the United States illegally. Third, since all arrests for an individual may not be recorded in IAFIS, our data represent the minimum number of arrests for these illegal aliens. Last, our analysis is not designed to infer conclusions about the arrest history of other illegal aliens not in our study population who entered the country illegally and have been arrested. In April, we discussed with your offices the results of our work. This report conveys the information provided during those discussions (see encl. I). We performed our work from October 2004 through May 2005 in accordance with generally accepted government auditing standards. Further details on our scope and methodology, including how we selected the illegal aliens in our study population, are discussed in enclosure II. Results: The briefing slides in enclosure I address each of our three questions. In summary, for our study population of 55,322 illegal aliens, we found that: * They were arrested at least a total of 459,614 times, averaging about 8 arrests per illegal alien. Nearly all had more than 1 arrest. Thirty- eight percent (about 21,000) had between 2 and 5 arrests, 32 percent (about 18,000) had between 6 and 10 arrests, and 26 percent (about 15,000) had 11 or more arrests. Most of the arrests occurred after 1990. * They were arrested for a total of about 700,000 criminal offenses, averaging about 13 offenses per illegal alien. One arrest incident may include multiple offenses, a fact that explains why there are nearly one and half times more offenses than arrests.[Footnote 6] Almost all of these illegal aliens were arrested for more than 1 offense. Slightly more than half of the 55,322 illegal aliens had between 2 and 10 offenses. About 45 percent of all offenses were drug or immigration offenses. About 15 percent were property-related offenses such as burglary, larceny-theft, motor vehicle theft, and property damage. About 12 percent were for violent offenses such as murder, robbery, assault, and sex-related crimes. The balance was for such other offenses as traffic violations, including driving under the influence; fraud--including forgery and counterfeiting; weapons violations; and obstruction of justice. * Eighty percent of all arrests occurred in three states--California, Texas, and Arizona. Specifically, about 58 percent of all arrests occurred in California, 14 percent in Texas, and 8 percent in Arizona. Agency Comments and Our Evaluation: The Departments of Justice and Homeland Security reviewed a draft of this report and had technical comments, which we incorporated as appropriate. We are sending copies to the Departments of Justice and Homeland Security and interested congressional committees, and we will make copies available to others who request them. In addition, the report will be available at no charge on GAO's Web site at http://www.gao.gov. If you or your staff have any questions concerning this report, please contact me at (202) 512-8816 or by e-mail at Stanar@gao.gov or Michael Dino, Assistant Director, at (213) 830-1150 or Dinom@gao.gov. Key contributors to this report were Amy Bernstein, Ann H. Finley, Evan Gilman, Frederick Lyles, Jr., Jan Montgomery, Karen O'Conor, Jason Schwartz, and Laura Czohara. Sincerely yours, Signed by: Richard M. Stana, Director, Homeland Security and Justice Issues: [End of section] Enclosure I: Briefing Slides: Information on Certain Illegal Aliens Arrested in the United States: Briefing for Congressional Requesters: April 2005: Introduction: In April 2005, we issued a report, Information on Criminal Aliens Incarcerated in Federal and State Prisons and Local Jails, (GAO-05- 337R). This report contained information on the number of criminal aliens we identified that were incarcerated, their country of citizenship or country of birth, and the cost to incarcerate them. You also requested that we provide information on the criminal history of aliens incarcerated in federal and state prisons or local jails who had entered the country illegally. Objectives: For a population of aliens incarcerated in federal and state prisons and local jails during fiscal year 2003 who entered the country illegally, we address the following questions: (1) How many arrests did they have? (2) How many and what type of criminal offenses have they been arrested for? (3) What states were they arrested in? Results in Brief: How many arrests did these illegal aliens have? For our study population of 55,322 illegal aliens: * They were arrested at least a total of 459,614 times, averaging about 8 arrests per illegal alien.[Note 1] * Ninety-seven percent had more than 1 arrest. About 38 percent had between 2 and 5 arrests, 32 percent had between 6 and 10 arrests, and 26 percent had over 11 arrests. * Eighty-one percent of all arrests occurred after 1990. [1] An arrest does not necessarily result in a prosecution or a conviction. Results in Brief: How many and what type of criminal offenses were they arrested for? For our study population of 55,322 illegal aliens: * They were arrested for at least a total of nearly 700,000 criminal offenses, averaging 13 offenses per alien. * About 24 percent were drug offenses. * About 21 percent were immigration offenses. * About 15 percent were property-related offenses such as burglary, larceny-theft, motor vehicle theft, and property damage. * About 12 percent were for murder, robbery, assault, and sexually related crimes. * The remaining 28 percent were for other offenses such as traffic violations, including driving under the influence; fraud—including forgery and counterfeiting; weapons violations; and obstruction of justice. Results in Brief: What states were they arrested in? For our study population of 55,322 illegal aliens: * Eighty percent of all arrests occurred in the following 3 states. California: 58 percent. Texas: 14 percent. Arizona: 8 percent. Background: When an individual is taken into custody, the arresting law enforcement agency captures the arrest charge(s), fingerprints, and personal identifiers of the individual. This information is submitted to the FBI’s Integrated Automated Fingerprint Identification System (IAFIS), which is responsible for preserving identification and criminal history records for felony and serious misdemeanor offenses. The FBI assigns an FBI identification number to each set of fingerprints. Generally, all aliens arrested by the DHS’s U.S. Immigration and Customs Enforcement (ICE) are assigned an alien identification number. This allows ICE to establish and track an alien’s immigration history. For illegal aliens incarcerated in state prisons and local jails, the federal government has reimbursed state and local governments that apply for reimbursement for a portion of their incarceration costs through the Department of Justice’s (DOJ) State Criminal Alien Assistance Program (SCAAP), managed by the Bureau of Justice Assistance (BJA). Scope and Methodology—Study Population of Illegal Aliens Used in Our Analysis: Number of convicted criminal aliens; Inmates incarcerated in federal prison on December 27, 2003: 46,063; Inmates incarcerated by state prisons and local jails and submitted to SCAAP for reimbursement[NOTE 1]: 262,105. Number of unique convicted criminal aliens with a FBI identification number and an alien identification number Inmates incarcerated in federal prison on December 27, 2003: 36,390; Inmates incarcerated by state prisons and local jails and submitted to SCAAP for reimbursement[NOTE 1]: 59,427. Number of the above unique convicted criminal aliens that ICE determined to have entered illegally; Inmates incarcerated in federal prison on December 27, 2003: 18,581; Inmates incarcerated by state prisons and local jails and submitted to SCAAP for reimbursement[NOTE 1]: 36,741. Total study population of illegal aliens used in our analysis: 55,322. [1] These represent the inmates incarcerated in state prisons and local jails between July 1, 2002, and June 30, 2003. [End of table] Scope and Methodology—Analysis of Arrest Data: * For the 55,322 illegal aliens in our study population, we obtained and analyzed the arrest history information contained in IAFIS as of October 2004. * The arrest history information contained the date of arrest; the arresting federal, state, or local law enforcement agency; and a narrative description of the offense for which the alien was arrested. * For purposes of our analysis, we categorized these arrest descriptions into 1 of 19 major offense categories, e.g., immigration, drugs (see slides 10 and 11). * In addition, for the 18,581 illegal aliens in our study population who were incarcerated in a federal prison, we analyzed related conviction information. Note: Under 28 U.S.C. 534, the FBI is required to acquire, collect, classify, and preserve, among other things, identification and criminal records. IAFIS includes individuals who have been arrested for an offense that is classified as a felony or a serious misdemeanor. Scope and Methodology—Crimes Included in Major Offense Categories: Major offense category[1]: Arson; Category includes: arson, reckless burning, and possession of arson materials. Major offense category[1]: Assault; Category includes: assault, battery, assault with a deadly weapon, endangerment, and threats. Major offense category[1]: Burglary; Category includes: breaking and entering, burglary, and possession of burglary tools. Major offense category[1]: Disorderly conduct; Category includes: disturbing the peace, fighting, intoxication, public nuisance, and disorderly conduct. Major offense category[1]: Drugs; Category includes: use/under the influence, possession, possession with intent to distribute, sales, manufacturing, transporting, and possession of drug paraphernalia. Major offense category[1]: Fraud, forgery, and counterfeiting; Category includes: deceptive practices or identification, fraud, giving false information, altering or forging documents, and counterfeiting or possession of counterfeit materials or tools. Major offense category[1]: Homicide; Category includes: murder, manslaughter, and homicide. Major offense category[1]: Immigration; Category includes: illegal entry, illegal reentry, false claim to U.S. citizenship, alien smuggling, and removal proceedings. Major offense category[1]: Kidnapping; Category includes: false imprisonment, kidnapping, and taking hostages. Major offense category[1]: Larceny/theft; Category includes: grand and petty larceny and theft, shoplifting, embezzlement, and money laundering. Major offense category[1]: Motor vehicle theft; Category includes: auto theft, carjacking, and taking a vehicle without consent. Major offense category[1]: Obstruction of justice; Category includes: escaping, evading, being a fugitive of justice, failing to appear, failing to register as a sex offender, resisting arrest, and interfering with or obstructing an officer or justice proceedings. Major offense category[1]: Property damage; Category includes: destruction of property, vandalism, and criminal or malicious mischief. Major offense category[1]: Robbery; Category includes: armed robbery, robbery of a dwelling, robbery of a bank, and unarmed robbery. Major offense category[1]: Sex offenses; Category includes: lewd and lascivious acts, rape, sexual assault, indecent exposure, prostitution, and molestation. Major offense category[1]: Stolen property; Category includes: buying, selling, receiving, or possessing stolen property. Major offense category[1]: Traffic violations; Category includes: driving under the influence, hit and run, no proof of insurance, no driver’s license, and moving violations such as speeding and failure to stop. Major offense category[1]: Weapons violations; Category includes: possession of a weapon, discharging a weapon, altering a weapon, and carrying a concealed weapon. Major offense category[1]: Other; Category includes: includes trespassing, gang participation, littering, child cruelty, racketeering, and illegal waste dumping. [1] All offenses include any attempt or conspiracy to commit the respective offense. We developed the criminal offense categories using the FBI’s classification for offense codes as our guidance. [End of table] Data Limitations: * The FBI’s IAFIS does not include all arrests and offenses–7 states[note 1] report only the first arrest and associated offenses to the FBI, subsequent arrest information is available only through the state’s criminal history database. Further, some law enforcement agencies do not report information on every arrest to the FBI. Also, IAFIS does not include minor misdemeanor offenses. * FBI may reject fingerprint cards that are not readable, and sometimes the submitting law enforcement agency does not resubmit the card for entry into IAFIS. * Results of our analysis pertain only to our study population. Results cannot be generalized to all illegal aliens that may have been arrested and therefore cannot be interpreted as representing arrest or offense rates for all illegal aliens. NOTE 1: Colorado, Florida, Montana, Oklahoma, Oregon, New Jersey, and North Carolina. Number of Arrests: Ninety-seven percent of illegal aliens in our study population had more than one arrest: [See PDF for image] [End of figure] Number of Arrests: Federal Prison Inmates: Ninety-nine percent of incarcerated illegal aliens had more than one arrest: [See PDF for image] [End of figure] Number of Arrests: State Prison and Local Jail Inmates: Ninety-six percent of incarcerated illegal aliens had more than one arrest: [See PDF for image] [End of figure] Arrest Offenses: Illegal aliens in our study population were arrested for almost 700,000 offenses, averaging 13 offenses per illegal alien[A]: * Number of illegal aliens in our study population: 55,322. * Total number of arrests[B]: 459,614. * Total number of criminal offenses: 691,890. * Average number of criminal offenses per illegal alien: 13. * Median number of criminal offenses per illegal alien: 10. [A] One arrest incident may include multiple offenses. [B] For the study population of illegal aliens, the analysis time frame covers arrests recorded in the FBI’s IAFIS—dating from 1947 to October 28, 2004. Source: GAO analysis of FBI IAFIS data. [End of table] Number of Offenses: Ninety-eight percent of illegal aliens in our total study population were arrested for two or more offenses: [See PDF for image] [End of figure] Arrest Offenses: Forty-five percent of illegal alien offenses were for drugs and immigration: Criminal offense: Drugs; Total offenses: Number: 166,722; Total offenses: Percent: 24%; Offenses for illegal aliens in federal prisons: Number: 64,737; Offenses for illegal aliens in federal prisons: Percent: 24%; Offenses for illegal aliens in state prisons and local jails: Number: 101,985; Offenses for illegal aliens in state prisons and local jails: Percent: 24%. Criminal offense: Immigration; Total offenses: Number: 144,166; Total offenses: Percent: 21%; Offenses for illegal aliens in federal prisons: Number: 84,382; Offenses for illegal aliens in federal prisons: Percent: 32%; Offenses for illegal aliens in state prisons and local jails: Number: 59,784; Offenses for illegal aliens in state prisons and local jails: Percent: 14%. Criminal offense: Traffic violations; Total offenses: Number: 55,060; Total offenses: Percent: 8%; Offenses for illegal aliens in federal prisons: Number: 13,290; Offenses for illegal aliens in federal prisons: Percent: 5%; Offenses for illegal aliens in state prisons and local jails: Number: 41,770; Offenses for illegal aliens in state prisons and local jails: Percent: 10%. Criminal offense: Assault; Total offenses: Number: 50,958; Total offenses: Percent: 7%; Offenses for illegal aliens in federal prisons: Number: 14,908; Offenses for illegal aliens in federal prisons: Percent: 6%; Offenses for illegal aliens in state prisons and local jails: Number: 36,050; Offenses for illegal aliens in state prisons and local jails: Percent: 8%. Criminal offense: Obstruction of justice; Total offenses: Number: 45,632; Total offenses: Percent: 7%; Offenses for illegal aliens in federal prisons: Number: 15,064; Offenses for illegal aliens in federal prisons: Percent: 6%; Offenses for illegal aliens in state prisons and local jails: Number: 30,568; Offenses for illegal aliens in state prisons and local jails: Percent: 7%. Criminal offense: Burglary; Total offenses: Number: 38,689; Total offenses: Percent: 6%; Offenses for illegal aliens in federal prisons: Number: 13,156; Offenses for illegal aliens in federal prisons: Percent: 5%; Offenses for illegal aliens in state prisons and local jails: Number: 25,533; Offenses for illegal aliens in state prisons and local jails: Percent: 6%. Criminal offense: Larceny/theft; Total offenses: Number: 31,883; Total offenses: Percent: 5%; Offenses for illegal aliens in federal prisons: Number: 12,206; Offenses for illegal aliens in federal prisons: Percent: 5%; Offenses for illegal aliens in state prisons and local jails: Number: 19,677; Offenses for illegal aliens in state prisons and local jails: Percent: 5%. Criminal offense: Fraud, forgery, and counterfeiting; Total offenses: Number: 25,773; Total offenses: Percent: 4%; Offenses for illegal aliens in federal prisons: Number: 8,564; Offenses for illegal aliens in federal prisons: Percent: 3%; Offenses for illegal aliens in state prisons and local jails: Number: 17,209; Offenses for illegal aliens in state prisons and local jails: Percent: 4%. Criminal offense: Weapons violations; Total offenses: Number: 22,263; Total offenses: Percent: 3%; Offenses for illegal aliens in federal prisons: Number: 7,236; Offenses for illegal aliens in federal prisons: Percent: 3%; Offenses for illegal aliens in state prisons and local jails: Number: 15,027; Offenses for illegal aliens in state prisons and local jails: Percent: 4%. Criminal offense: Motor vehicle theft; Total offenses: Number: 20,950; Total offenses: Percent: 3%; Offenses for illegal aliens in federal prisons: Number: 6,494; Offenses for illegal aliens in federal prisons: Percent: 2%; Offenses for illegal aliens in state prisons and local jails: Number: 14,456; Offenses for illegal aliens in state prisons and local jails: Percent: 3%. Criminal offense: Robbery; Total offenses: Number: 15,305; Total offenses: Percent: 2%; Offenses for illegal aliens in federal prisons: Number: 4,177; Offenses for illegal aliens in federal prisons: Percent: 2%; Offenses for illegal aliens in state prisons and local jails: Number: 11,128; Offenses for illegal aliens in state prisons and local jails: Percent: 3%. Criminal offense: Stolen property; Total offenses: Number: 13,415; Total offenses: Percent: 2%; Offenses for illegal aliens in federal prisons: Number: 4,201; Offenses for illegal aliens in federal prisons: Percent: 2%; Offenses for illegal aliens in state prisons and local jails: Number: 9,214; Offenses for illegal aliens in state prisons and local jails: Percent: 2%. Criminal offense: Sex offense; Total offenses: Number: 11,833; Total offenses: Percent: 2%; Offenses for illegal aliens in federal prisons: Number: 2,501; Offenses for illegal aliens in federal prisons: Percent: 1%; Offenses for illegal aliens in state prisons and local jails: Number: 9,332; Offenses for illegal aliens in state prisons and local jails: Percent: 2%. Criminal offense: Disorderly conduct; Total offenses: Number: 8,768; Total offenses: Percent: 1%; Offenses for illegal aliens in federal prisons: Number: 2,986; Offenses for illegal aliens in federal prisons: Percent: 1%; Offenses for illegal aliens in state prisons and local jails: Number: 5,782; Offenses for illegal aliens in state prisons and local jails: Percent: 1%. Criminal offense: Property damage; Total offenses: Number: 6,478; Total offenses: Percent: 1%; Offenses for illegal aliens in federal prisons: Number: 2,238; Offenses for illegal aliens in federal prisons: Percent: 1%; Offenses for illegal aliens in state prisons and local jails: Number: 4,240; Offenses for illegal aliens in state prisons and local jails: Percent: 1%. Criminal offense: Homicide; Total offenses: Number: 5,992; Total offenses: Percent: 1%; Offenses for illegal aliens in federal prisons: Number: 1,156; Offenses for illegal aliens in federal prisons: Percent: <1%; Offenses for illegal aliens in state prisons and local jails: Number: 4,836; Offenses for illegal aliens in state prisons and local jails: Percent: 1%. Criminal offense: Kidnapping; Total offenses: Number: 3,236; Total offenses: Percent: <1%; Offenses for illegal aliens in federal prisons: Number: 837; Offenses for illegal aliens in federal prisons: Percent: <1%; Offenses for illegal aliens in state prisons and local jails: Number: 2,399; Offenses for illegal aliens in state prisons and local jails: Percent: 1%. Criminal offense: Arson; Total offenses: Number: 457; Total offenses: Percent: <1%; Offenses for illegal aliens in federal prisons: Number: 173; Offenses for illegal aliens in federal prisons: Percent: <1%; Offenses for illegal aliens in state prisons and local jails: Number: 284; Offenses for illegal aliens in state prisons and local jails: Percent: <1%. Criminal offense: Other; Total offenses: Number: 24,310; Total offenses: Percent: 4%; Offenses for illegal aliens in federal prisons: Number: 9,403; Offenses for illegal aliens in federal prisons: Percent: 4%; Offenses for illegal aliens in state prisons and local jails: Number: 14,907; Offenses for illegal aliens in state prisons and local jails: Percent: 4%. Total; Total offenses: Number: 691,890; Total offenses: Percent: 100%; Offenses for illegal aliens in federal prisons: Number: 267,709; Offenses for illegal aliens in federal prisons: Percent: 100%; Offenses for illegal aliens in state prisons and local jails: Number: 424,181; Offenses for illegal aliens in state prisons and local jails: Percent: 100%. [End of table] Convictions: Federal Prison Illegal Alien Inmates: Almost 90 percent of this portion of our study population was convicted of immigration or drug offenses: Offense: Immigration; Number: 12,694; Percent: 68%. Offense: Drugs; Number: 3,978; Percent: 21%. Offense: Unknown; Number: 1,183; Percent: 6%. Offense: Weapons, explosives, arson; Number: 251; Percent: 1%. Offense: Fraud, bribery, extortion ; Number: 185; Percent: 1%. Offense: Burglary, larceny, property crimes; Number: 95; Percent: 1%. Offense: Assault; Number: 41; Percent: <1%. Offense: Robbery; Number: 28; Percent: <1%. Offense: Kidnapping; Number: 26; Percent: <1%. Offense: Court, corrections; Number: 25; Percent: <1%. Offense: Homicide; Number: 13; Percent: <1%. Offense: Other; Number: 62; Percent: <1%. Offense: Totals; Number: 18,581; Percent: 100.00%. [End of table] Location of Arrests: Illegal Aliens In Our Study Population: Eighty percent of all arrests occurred in three states–California, Texas, and Arizona: [See PDF for image] [End of figure] Location of Arrests: Federal Prison Illegal Alien Inmates: Seventy-one percent of all arrests occurred in three states–California, Texas, and Arizona: [See PDF for image] [End of figure] Location of Arrests: State Prison and Local Jail Illegal Alien Inmates: Eighty-seven percent of all arrests occurred in three states–California, Texas, and Arizona: [See PDF for image] [End of figure] [End of slide presentation] [End of section] Enclosure II: Objectives, Scope, and Methodology: Using data we had obtained for our report, Information on Criminal Aliens Incarcerated in Federal and State Prisons and Local Jails, GAO- 05-337R, we selected our study population of aliens that illegally entered the United States using the following methodology. We started with data we obtained from the Federal Bureau of Prisons (BOP) on the population of aliens incarcerated in federal prison as of December 27, 2003. We added to this the population of convicted criminal aliens incarcerated in state prisons and local jails between July 1, 2002, and June 30, 2003 for whom state and local governments sought reimbursement under the State Criminal Alien Assistance Program (SCAAP).[Footnote 7] These two populations were chosen because they were the latest population data we had when we began our analysis. From this combined population we identified those criminal aliens that had both an alien identification number and an FBI identification number in the data records we obtained. An alien identification number is a unique number assigned to an alien who has come into contact with immigration authorities. The FBI identification number is a unique identifier the FBI assigns to a set of fingerprints that allows linking relevant records of arrests and any subsequent activity within the criminal justice system. We needed to have alien identification numbers in order to be able to identify those aliens illegally in the United States and FBI numbers in order to obtain the relevant criminal history record information from the FBI. For those criminal aliens with both an alien identification number and an FBI identification number, we requested that the U.S. Immigration and Customs Enforcement (ICE) within the Department of Homeland Security identify those aliens that, according to their records, had entered the country illegally. For those aliens that ICE identified as having entered the country illegally, we provided the FBI number and other identifying information to the FBI and requested their criminal history records. The criminal history record for each unique FBI identification number contained the dates of each arrest, the arresting agency, an offense code,[Footnote 8] and a literal description of each offense for which the alien was arrested, e.g., drug possession, burglary, robbery. The arrest information for each illegal alien is all arrests recorded in IAFIS as of October 28, 2004. Table 1 describes the number of criminal aliens at each level of our analysis. Table 1: Selection of Illegal Alien Study Population Used For Our Analysis: Number of convicted criminal aliens; Inmates incarcerated in federal prison on December 27, 2003: 46,063; Inmates incarcerated by state prisons and local jails between July 1, 2002, and June 30, 2003, and submitted to SCAAP for reimbursement: 262,105. Number of unique convicted criminal aliens with a FBI identification number and an alien identification number; Inmates incarcerated in federal prison on December 27, 2003: 36,390; Inmates incarcerated by state prisons and local jails between July 1, 2002, and June 30, 2003, and submitted to SCAAP for reimbursement: 59,427. Number of the above unique convicted criminal aliens that ICE determined to have entered illegally; Inmates incarcerated in federal prison on December 27, 2003: 18,581; Inmates incarcerated by state prisons and local jails between July 1, 2002, and June 30, 2003, and submitted to SCAAP for reimbursement: 36,741. Total population of illegal aliens used in our analysis; Inmates incarcerated in federal prison on December 27, 2003: 55,322. Source: GAO: [End of table] To determine the number of arrests for our study population of illegal aliens, we totaled the number of unique dates of arrest for each unique FBI number contained in the FBI criminal history records we obtained. The earliest arrest record was in 1947, the latest October 28, 2004. The criminal history records contained several hundred thousand different literal descriptions of arrest offenses. To determine the offenses for which these illegal aliens were arrested, we categorized the arrest descriptions contained in the criminal history records into 1 of 19 major offense categories (e.g., immigration, drugs) using FBI guidance to law enforcement agencies on how to categorize different types of crimes. FBI officials concurred with the way we categorized the literal descriptions into the 19 major offense categories. To identify the states these illegal aliens were arrested in, we analyzed the data contained in the arresting agency field of the criminal history record for each unique date of arrest. Data Reliability: We determined that the BOP data are sufficiently reliable for the purposes of this report. To assess the reliability of the data, we discussed with responsible BOP officials how data on the number of federal inmates and whether they are a citizen or an alien are collected and maintained in BOP's inmate tracking system called SENTRY. We reviewed BOP policies and procedures related to entering data into the SENTRY system and reviewed a Department of Justice Inspector General review of the SENTRY system. We determined that SCAAP data are sufficiently reliable for the purposes of this report. To assess the reliability of the SCAAP data, we discussed with responsible BJA officials how data on criminal aliens reimbursed through SCAAP are collected and maintained. We reviewed BJA SCAAP policies and procedures and guidance on how state and local jurisdictions can apply for reimbursement under the program. State and local jurisdictions submit inmates to BJA for reimbursement based on the inmates' self-reporting their country of citizenship or place of birth. The state and local jurisdictions certify they have exercised due diligence in determining which inmates qualify for reimbursement and the inmates' data, such as name and if available, alien identification and FBI identification numbers. We determined that ICE data are sufficiently reliable for the purposes of this report. To assess the reliability of ICE's determination that aliens with both an alien identification number and an FBI identification number had entered illegally, we discussed with the ICE official who conducted the analysis the process he used to make this determination. The determination was made after querying several immigration databases using the unique alien identification number we had supplied. We determined that the FBI's IAFIS data on arrests are sufficiently reliable for the purposes of this report. To assess the reliability of the data, we discussed with responsible FBI officials how data on arrests are collected and maintained in IAFIS. We reviewed FBI policies and procedures related to entering data into the FBI system. The FBI estimates 8 percent of the criminal arrests are no longer maintained by the FBI because 7 states, Colorado, Florida, Montana, Oklahoma, Oregon, New Jersey, and North Carolina only report their first arrest to the FBI. We performed our work from October 2004 through May 2005 in accordance with generally accepted government auditing standards. FOOTNOTES [1] Estimates of the Unauthorized Immigrant Population Residing in the United States: 1990 to 2000, Office of Policy and Planning, U.S. Immigration and Naturalization Service. [2] Estimates of the Size and Characteristics of the Undocumented Population, Jeffrey S. Passel, Pew Hispanic Research Center, March 2005. [3] An alien legally or illegally in the United States who has been convicted of a crime. [4] GAO, Information on Criminal Aliens Incarcerated in Federal and State Prisons and Local Jails, GAO-05-337R (Washington, D.C.: April 7, 2005). [5] IAFIS contains the fingerprints and corresponding criminal history for more than 47 million subjects. The fingerprints and corresponding criminal history information are submitted voluntarily by federal, state and local law enforcement agencies. [6] For example, a burglar may enter a home, steal some of the victim's property, and drive away in the victim's car. If arrested, the person could be charged with three offenses, burglary, theft, and motor vehicle theft. [7] The Department of Justice Bureau of Justice Assistance (BJA) program that reimburses state and local governments for a portion of their costs of incarcerating some, but not all, criminal aliens illegally in the country. [8] A numeric code that the arresting law enforcement agency assigns to the criminal offense.