Posted on October 12, 2022

Misuse of Texas Data Understates Illegal Immigrant Criminality

Sean Kennedy et al., Center for Immigration Studies, October 11, 2022


Activists and academics have been misusing data from the Texas Department of Public Safety (DPS) in studies claiming that illegal immigrants have relatively low crime rates. These studies do not appreciate that it can take years for Texas to identify convicts as illegal immigrants while they are in custody. As a result, the studies misclassify as native-born a significant number of offenders who are later identified as illegal immigrants.

Facts About the DPS Data:

  • Due to delays in identification, the number of illegal immigrants arrested or incarcerated in Texas is undercounted at any given time.
  • Recently convicted illegal immigrants are the most likely to be undercounted.
  • Conversely, Texas is more likely to ascertain the immigration status of offenders who have served long prison terms for serious crimes.
  • The illegal immigrant conviction rate for “any crime” — which would be dominated by offenses requiring little or no prison time — is not meaningful due to undercount.

Properly interpreted, the DPS data suggests that illegal immigrants in Texas are convicted of homicide and sexual assault at higher rates than the state average. Significant uncertainties remain, however, especially regarding lesser offenses.


When people are arrested in Texas, the state’s Department of Public Safety (DPS) sends their fingerprints to the federal Department of Homeland Security (DHS) to determine immigration status. Illegal immigrants who have had encounters with immigration officials, such as at the border or during a prior arrest, will be identified by DHS and then flagged as illegal in the DPS data. However, the immigration status of a significant share of immigrants arrested in Texas cannot be verified by this system because immigration officials have never encountered them. Therefore, the Texas Department of Criminal Justice (DCJ) continues to investigate the immigration status of offenders while they are incarcerated.


Figure 1 demonstrates how failing to understand this undercount can lead to erroneous conclusions about illegal immigrant crime rates. If we counted only the illegal immigrants who were initially identified by DHS when arrested for homicide, the 2012 homicide rate (convictions divided by population) would be 2.7 per 100,000 illegal immigrants in the state, as depicted in the light-blue bar. This rate, while hardly trivial, is lower than the state’s overall homicide conviction rate of 3.0 (orange bar) in 2012.

However, once the illegal immigrants identified during their prison stays are added to the total count of illegals, their homicide rate rises to 3.9 per 100,000 (dark-blue bar) in 2012. This rate is higher than the state average, and it could rise even further as more illegal immigrants continue to be identified in prison.


Mistaken Studies

Recent studies using DPS data understate the extent of illegal immigrant crime by ignoring or downplaying the fact that many arrestees and convicts move from “other/unknown” to illegal over time.

Cato Institute. In February 2018, the Cato Institute’s Alex Nowrasteh released his analysis of 2015 DPS data.3 He concluded that “the conviction and arrest rates for illegal immigrants were lower than those for native-born Americans.” This conclusion was highlighted by the New York Times, Washington Post, NPR, and many other outlets.

Nowrasteh’s error was to treat as native-born anyone who had not yet been categorized as a legal or illegal immigrant. He failed to understand the DPS “other/unknown” category and the movement of illegal immigrants out of that category over time. As discussed above, “native-born” is not a category verified by DPS. Native-born Americans are grouped with yet-to-be-identified immigrants in a catch-all category called “other/unknown”. The number of unknowns shrinks during incarceration as Texas updates the figures upon identification of an inmate’s immigration status.


Studies purporting to show low illegal immigrant crime rates in Texas fail to account for the fact that illegal immigrants are not always identified immediately upon arrest. In many cases, illegal immigrants are identified only after they are imprisoned. Given sufficient time for data collection, it appears that illegal immigrants have above average conviction rates for homicide and sexual assault, while they have lower rates for robbery and drugs. Significant uncertainty persists, however, as to how many illegals may remain unidentified, especially those who committed lesser offenses requiring little or no prison time. While strong claims about the overall criminality of illegal immigrants are not possible with the current data, prior research has understated it substantially.