Daron Wint should never have been in a position to murder four people in a Washington, D.C. home last month. For more than a decade before the so-called Mansion Murders, Wint had apparently led a life of violent crime. He had immigrated from Guyana legally in 2000, but he should have been sent back years ago.

Opponents of immigration reform blame the Mansion Murders on lax enforcement of our immigration laws under the Obama administration, yet the killings actually support the case that immigration advocates have been making for years: that enforcement should focus on those who harm the person or property of others.

{mosads}Federal agencies spend almost $18 billion per year enforcing immigration, customs, and trafficking laws, a budget 25 percent higher than the combined budgets of the FBI, DEA, Secret Service, U.S. Marshals, and Bureau of Alcohol, Tobacco, Firearms and Explosives. Since 2000, border-patrol and interior immigration agents have apprehended more than 15 million people for civil violations of immigration law. That’s more than the populations of 46 states.

The government is spending billions and rounding up masses of people larger than many countries, yet somehow Daron Wint was not marked for deportation until he murdered several people. This is despite the fact that he had more than two dozen run-ins with law enforcement since coming to the United States. In 2007 he stabbed a man on two separate occasions and assaulted the man’s girlfriend, crimes for which he served three months in jail.

Certainly Wint’s presence in D.C. this year was a failure of law enforcement. But those wishing to blame Obama’s recent executive actions granting relief from deportation to certain immigrants who are here illegally should look elsewhere. After all, the stabbings took place in 2007 during the Bush administration, and besides, Wint was actually here legally.

The government failed, but the question now is: what sorts of policies would be best suited to prevent a repeat of Wint’s atrocities? The fact is that indiscriminate immigration enforcement puts too much attention on peaceful immigrants—families, workers, and asylum seekers—and not enough on felons like Wint.

Even the Obama administration, which portrays itself as engaging in only the most targeted immigration enforcement, continues to deport people for traffic violations and place thousands of small children and mothers in jail-like detention centers. It still apprehends hundreds of thousands of ordinary people at the border who seek to work or reunite with family here.

The answer is not to throw up our hands and say, “We surrender.” Rather than giving up on enforcement of the laws, Congress needs to narrow its focus to only those people who are likely to harm Americans. It should scrap its obsession with enforcing its way out of illegal immigration and legalize immigration for workers and families in order to better criminalize immigration for those who violate the rights of Americans.

Is the government’s failure to stop Wint an argument against legal immigration? No, in fact, immigrants may actually be driving the crime rate down.

As immigration spiked in the 1990s, violent crime plunged to record lows. From 1990 to 2013, the foreign-born population exploded from 7.9 percent of the population to 13.1 percent. During this time, the violent crime rate fell from about 750 offenses per 100,000 people to under 400 offenses. Property crime fell by a dramatic 43 percent. Immigrants are not causing a crime wave.

While we may not know how much of this fall was due to immigrants, but government data do show that immigrants have a much lower incarceration rate than natives and are generally less likely to commit crimes. These facts explain why immigrant-heavy communities have lower rates of crime.

The government cannot stop all crime by citizens or noncitizens. Attempting such a feat would be a ludicrous strategy of pre-crime prosecution and lead back to the failed policy of indiscriminate enforcement. What it can do is concentrate its efforts on actual threats and real criminals, not on peaceful people seeking a better life for themselves in the United States.

A better immigration system would better protect America.

Bier is an immigration policy expert at the Niskanen Center, a nonprofit in Washington, D.C.