President Trump appears to be using the murder of a 20-year-old University of Iowa student to frame the national debate on immigration.

“Mollie Tibbetts, an incredible young woman, is now permanently separated from her family,” Mr. Trump said in a video posted on Twitter. “A person came in from Mexico illegally and killed her. We need the wall, we need our immigration laws changed, we need our border laws changed, we need Republicans to do it because the Democrats aren’t going to do it.”

Authorities have charged Cristhian Bahena Rivera with the murder of Ms. Tibbetts, who had been missing since July. Mr. Rivera, an undocumented immigrant, led authorities to a body suspected to be Ms. Tibbetts on Tuesday, according to the Associated Press.

Ms. Tibbetts’s second cousin, Sam Lucas, accused the president and his supporters of politicizing the murder on Twitter: “attn Trumpists: Mollie’s death is not political propaganda to bring up your ‘build the wall’ bulls—.”

“This is a horrific crime and tragedy, and justice should be served,” Mr. Appleby said of Ms. Tibbetts’s death.

Political analysts have long anticipated that immigration would take center stage leading into the midterm elections. Immigration reform and border security are also expected to be major issues in upcoming federal budget negotiations.

“The president has turned immigration into simply good people, bad people and a wall,” said Christopher Kerr, the executive director of the Ignatian Solidarity Network. “Immigrants are moms and dads and children. They’re in the same schools, shop at the same grocery stores as we do. They’re not rapists or criminals or poison, as the president has said.”

According to the Center for Migration Studies in New York, multiple studies, including one by the libertarian Cato Institute, have confirmed that immigrants, legal or undocumented, are less likely than native-born citizens to commit serious crimes. “Immigrant communities are among the safest in the nation,” Kevin Appleby, the senior director of international immigration policy for the C.M.S., told America in an email.

From 1990 to 2013, the number of undocumented immigrants living in the United States rose from 3.5 million to 11 million. Yet the U.S. violent crime rate declined by 48 percent over the same period, according to F.B.I. data.. The idea that cases like the murder of Ms. Tibbetts by an undocumented immigrant are becoming more common is unsupported by these statistical trends.

“As Catholics, we believe they should be welcomed into the church, regardless of their legal status.”

“This is a horrific crime and tragedy, and justice should be served,” Mr. Appleby said of Ms. Tibbetts’s death. “However, such a tragedy should not be used to convict all immigrants for the act of one person or to dehumanize them collectively.”

The Ignatian Solidarity Network has sought to humanize immigrants through various campaigns, according to Mr. Kerr. Its campaign of hospitality in the United States and Canada has encouraged members of its network to get to know migrants in their communities. It has encouraged prayer for immigrant families, especially those separated at the U.S.-Mexico border. In churches, banners are placed that read, simply, “Immigrants and refugees welcome.”

“I have this dream that there will be a banner in every church,” Mr. Kerr said. “As Catholics, we believe they should be welcomed into the church, regardless of their legal status.”

“Immigrants and refugees make significant contributions to our country,” he said, noting that I.S.N. also advocates for recipients of Temporary Protected Status and recipients of the Deferred Action for Childhood Arrivals program. DACA, which was enacted by President Obama to protect undocumented immigrants who came to the United States as minors, has faced an uncertain fate since Attorney General Jeff Sessions attempted to end it a year ago.

“Immigrants and refugees should not be used as pawns,” Mr. Kerr said, paraphrasing the words of Pope Francis. “I worry that President Trump has done just that with DACA recipients, using them [as bargaining chips] to build his border wall.”

Ms. Tibbitts’s murder humanizes the reality of violent crime, Mr. Kerr said. “It’s good to talk about that,” he said. “But the human family is big. We have to humanize all of it.”

Material from the Associated Press was used in this report.

J.D. Long García is a senior editor at America.