The Murder of Mollie Tibbetts and Illegal Immigrant Crime: The Facts

Yesterday, authorities in Iowa charged 24-year old Cristhian Bahena Rivera with the murder of Mollie Tibbetts. Facts in these types of cases come out slowly and some details, substantive or minor, may change in the months ahead that could alter the correct view of this case. But nothing can change the fact that the murder of Tibbetts was a brutal and unforgivable act and that the murderer should be punished to the full extent of the law. Rivera is charged with that murder and there is a lot of evidence to support a conviction.    

This terrible murder is already feeding into a political firestorm. People with a political axe to grind, those who want to distract from the recent conviction of Paul Manafort and plea deal for Michael Cohen, and partisans who want to compare Tibbetts’ murder to the shooting of Kate Steinle in an effort to impact the upcoming November elections are already using the tragic murder of Tibbetts as an argument for increasing the enforcement of immigration laws against people who aren’t charged with murder or any real crime except violating international labor market regulations (immigration laws). They want to convict all illegal immigrants of this murder in the court of public opinion, not just the actual murderer.    

Scarce law enforcement resources should be devoted to solving and deterring the most serious crimes regardless of who commits them.  That is the best policy for saving American lives. That means that increased enforcement of our immigration laws is not a good way to prevent murders.  Illegal immigrants are less likely to be incarcerated for crimes in the United States than native-born Americans. Texas is the only state that keeps data on the number of convictions of illegal immigrants for specific crimes (I state versions of Public Interest Requests to every state). In Texas in 2015, the rate of convictions per 100,000 illegal immigrants was 16 percent lower below that of native-born Americans. That is little consolation to the victims and their families, but the population of illegal immigrants is less likely to be convicted of murder than native-born Americans in Texas. If nationwide incarceration rates by immigration status are any clue, that trend likely holds nationwide. 

I recently received new data from Texas on the number of convictions by crime and immigration status as well as the number of individuals convicted (they are slightly different). This Texas data is the best data that we have on the commission of murder by immigrants by specific legal status.  In 2016, 746 native-born Texans, 32 illegal immigrants, and 28 legal immigrants were convicted of homicide. In that year, the homicide conviction rate for native-born Americans is Texas was 3.2 per 100,000 natives while it was 1.8 per 100,000 illegal immigrants and 0.9 per 100,000 legal immigrants (Figure 1). The illegal immigrant conviction rate for homicide was 56 percent below that of native-born Americans in 2016 in Texas. 

To calculate those conviction rates, I used an estimate of the size of the illegal immigrant population in Texas as well as data from the American Community Survey for the number of native-born Americans and legal immigrants. The conviction rates are per each subpopulation of native-born Americans, illegal immigrants, and legal immigrants. Immigration status makes no difference in the reporting of serious crimes like murder or robbery, so these statistics aren’t likely to be biased. Furthermore, states are not likely to turn over illegal immigrants for removal prior to convicting them of serious crimes. 

The Texas homicide conviction rates are consistent with the peer-reviewed evidence on immigrant conviction rates over the last century. Even Mark Krikorian, the executive director of the nativist Center for Immigration Studies, admits that “A lot of data does suggest immigrants are less likely to be involved in crime.”     

Texas isn’t Iowa and the reality in the latter state could be markedly different, but the state of Texas probably represents a near-worst-case scenario because it borders Mexico, has a large illegal immigrant population, is governed by Republicans, did not have any sanctuary jurisdiction in 2016, and has a law and order reputation for severely enforcing its criminal laws.  If there is any state that will find and prosecute illegal immigrants for crime, it’s Texas.  It should be strong evidence that the illegal immigrant conviction rate for homicide there is so low.

Already, I can hear people objecting by stating “you don’t know the size of the illegal immigrant population, so it’s just an estimate.” They are correct but virtually everybody who disagrees with the estimated size of the illegal immigrant population, which all cluster around the same number regardless of the organization doing the estimating, assumes that there are more illegal immigrants than are commonly estimated.

The real number of illegal immigrants isn’t too far off from the accepted estimates but if those critics are correct and demographers are missing a large number of them, that means that illegal immigrant crime and homicide rates are even lower than reported here and elsewhere (the denominator increases but the numerator stays the same). Ann Coulter wrote that there are 36 million illegal immigrants in her best-selling book on immigration. If she turns out to be correct and those 36 million illegal immigrants are distributed across the United States just as they are now, meaning that there are about 5.8 million in Texas, then the illegal immigrant homicide rate in 2016 was actual 0.56 per 100,000 illegal immigrants rather than the 1.8 reported here. If Coulter is correct, then she has unwittingly proven that illegal immigrants have the lowest homicide conviction rate of any population in the United States. 

Public policy must be based on data and trends, not on horrific anecdotes like the murder of Mollie Tibbets. Using law enforcement agencies on the local, state, and federal level to deport illegal immigrants who haven’t committed any violent or property crimes as a means to prevent tragic murders is a spectacularly poor way to prevent crime and save American laws. Such a misallocation of government resources will likely result in more victims as the government would spend a lot of resources deporting people who pose no security threat whatsoever and those resources must come from elsewhere, likely from other law enforcement activities. Punish the murderer of Mollie Tibbetts, don’t punish those who share the same immigration status as him from crimes they didn’t commit.