Minnesota state Sen. Karin Housley on Wednesday seized on the killing of a young Iowa college student — and the reported confession of an immigrant with disputed legal status — to take the fight on the immigration issue to her Democratic opponent, U.S. Sen. Tina Smith.

Housley, a Republican from the Stillwater area, released a statement calling the murder a "preventable tragedy." She charged that Smith and "liberal Democrats … are more concerned about protecting criminal aliens than protecting innocent lives like Mollie Tibbetts."

Smith did not directly address Housley's attack: "This is an awful tragedy and my heart breaks for Mollie's family. I can imagine nothing worse than losing a child. The individual responsible for this heinous crime must be brought to justice and punished," Smith said in a statement to the Star Tribune.

Cristhian Bahena Rivera was charged with Tibbetts' murder Tuesday, and authorities said he was in the country illegally. But on Wednesday his lawyer filed a motion stating his client is living and working in Iowa legally.

On Wednesday, a member of Tibbetts' extended family, Sam Lucas, a recent graduate of the University of Missouri, tweeted angrily that the death should not be used as "political propaganda." In addition, Tibbetts' aunt, Billie Jo Calderwood, urged people in a Facebook post to remember that "evil comes in all colors."

Republicans — and especially President Donald Trump — have sought to shine a light on millions of people here in violation of American immigration law, and who Republicans say pose a threat to the nation's safety.

Democrats, outraged by the Trump administration's policy of separating families seeking asylum and other aggressive deportation tactics, have grown increasingly defiant, including calls from some — though not Smith — to abolish the Immigration and Customs Enforcement arm of the federal government.

In her statement, Smith detailed her own views on immigration: "Since coming to the Senate, I have voted to increase funding for border security by more than $25 billion. I also believe we need better intelligence and more effective technology at the border. And we need to make sure reform includes a tough but fair path to citizenship for people who are in this country working, paying taxes and contributing to our society."

Housley and Trump, who favor a border wall and want to force cities and states to aggressively enforce immigration laws, say violent crime is a natural outgrowth of an uncontrolled border.

According to a 2015 National Academy of Sciences report, however, "Immigrants are in fact much less likely to commit crime than natives, and the presence of large numbers of immigrants seems to lower crime rates."

Jessica Vaughan, the policy director of the Center for Immigration Studies, which favors tighter immigration controls, said the data are inconclusive. "Anyone who says they know the answer to that question is misleading you" because the vast majority of jurisdictions don't track the immigration status of criminals and the census data on the immigration status of the incarcerated is a flawed measure of crime rates, Vaughan said.

Vaughan said the relevant policy questions are about deterring people from coming, the swift removal of those who commit crimes and a crackdown on those who hire them.

Alex Nowrasteh, an immigration policy analyst with the Cato Institute, said it is clear that undocumented immigrants commit fewer crimes, citing a preponderance of peer-reviewed studies, including a Cato study of Texas, the rare jurisdiction that tracks the immigration status of criminals.

The problem with an emphasis on crime committed by immigrants not in the country legally, Nowrasteh said, is that "they're focusing government resources on a population less likely to commit murders. That's a waste of resources that could have been used to prevent murder in populations that are more likely to commit them."

Trump, who made immigration a centerpiece of his presidential campaign, is hammering Democrats on the issue in the run-up to the election that could decide which party controls Congress.

At a campaign rally in West Virginia Tuesday, Trump blamed faulty immigration law for Tibbetts' murder: "You heard about today with the illegal immigrant coming in, very sadly, from Mexico and you saw what happened to that incredible, beautiful young woman," Trump told the crowd in Charleston. "Should've never happened. Illegally in our country. We've had a huge impact, but the laws are so bad. The immigration laws are such a disgrace, we're getting them changed, but we have to get more Republicans. We have to get 'em."

Housley's campaign cited a string of public statements and votes by Smith since her appointment as senator in early 2018. Smith is against a border wall, and attacked Trump's order ending protections for Liberian Minnesotans from deportation. She also voted against a measure that would restrict law enforcement grant money to sanctuary jurisdictions, and a proposal by Iowa Sen. Charles Grassley to eliminate the diversity visa lottery program and limit which individuals can become naturalized citizens.

"It was a wake-up call for all of us to have a young innocent girl lace up her shoes and go for a run and be raped and murdered. It makes me think of my own daughters and how it could happen in any community," Housley said in a Star Tribune interview. "Tina Smith and the Democrats are part of the problem," she said.

The Smith campaign pointed to Housley's changing position on Trump's border wall. She told the Mankato Free Press in January that it's not feasible but is now attacking Smith for her opposition to the wall. The Grassley amendment, meanwhile, faced bipartisan opposition, including from 14 Republicans.

Although the Tibbetts murder has attracted national attention, Housley pointed to another recent case in which a woman was killed, this one in Minnesota. The man charged with fatally stabbing his ex-girlfriend in a Shakopee apartment before slashing his own throat has a criminal history that led to his deportation to Mexico, federal officials said Tuesday.

The Associated Press and the Washington Post contributed to this report.