Body Believed to Be That of Mollie Tibbetts, Iowa College Student, Is Found

A body believed to be that of Mollie Tibbetts, a 20-year-old student at the University of Iowa who vanished a month ago after going for a jog, was found on Tuesday morning, investigators announced. A 24-year-old undocumented immigrant has been charged with first-degree murder in the killing.

“The identity has not been confirmed, however, we believe it to be the body of Mollie Tibbetts,” Mr. Rahn said. The authorities did not say what the specific cause of death was; an autopsy is scheduled for Wednesday.

The man charged in the killing is Cristhian Bahena Rivera, who lives in rural Poweshiek County, where the killing happened. He had lived in the area for four to seven years, Mr. Rahn said. Mr. Rivera’s Facebook page indicated he was from Mexico, a contention that President Trump alluded to during a rally Tuesday evening in West Virginia.

“You heard about today with the illegal alien coming in, very sadly from Mexico, and you saw what happened to that incredible, beautiful young woman,” Mr. Trump said. “It 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.”

Investigators acquired security video during a neighborhood canvass, and a vehicle seen in the video was traced back to Mr. Rivera, Mr. Rahn said during the news conference in Iowa.

In the security video, Ms. Tibbetts is seen running near Boundary and Middle Streets, and a dark-colored Chevy Malibu also appears, driving back and forth numerous times, according to an affidavit of probable cause filed Tuesday.

Mr. Rivera was questioned by law enforcement officers on Monday, and he admitted to pursuing a woman running in the area with his car, according to the affidavit. He told the authorities that he parked his car, got out and ran behind and beside her. Mr. Rivera said she then grabbed her phone and said, “I’m gonna call the police,” and he panicked, the affidavit said.

He told the authorities that he “blocked” his memory of what happened next, which he said happens when he gets upset, but recalled that he came to an intersection in his car and turned back around to an entrance of a cornfield, according to the affidavit.

Mr. Rivera said that he noticed there was an ear piece from a pair of headphones in his lap, and that is when he realized he had put the woman in the trunk of his car, according to the affidavit. He told the authorities that he then took her out of the trunk, noticing she had blood on the side of her head, before he put her over his shoulder and left her about 20 meters into the cornfield. He described placing corn leaves on her and leaving her face up, the affidavit said.

He later led the authorities to the body.

Based on the clothing found, and a tentative identification by the medical examiner, the authorities believe the body is that of Ms. Tibbetts.

“He tells us that he had seen her before,” Mr. Rahn said, but declined to elaborate on whether Mr. Rivera and Ms. Tibbetts knew each other.

Ms. Tibbetts was last seen on the evening of July 18 while running in her hometown, Brooklyn, a small town between Des Moines and Cedar Rapids. Her family reported her missing the next day.

At the time, she was dog-sitting for her boyfriend, Dalton Jack, and his brother, who live in Brooklyn and were out of town, Mr. Jack recently told Fox News.

“She regularly jogged around Brooklyn,” he said. “I’d say her route was pretty sporadic.”

Devin Riley, who said he saw Ms. Tibbetts jog past his house at about 8 p.m. on the night she disappeared, told ABC News that she would run by three or four times a week.

When he saw her on July 18 he thought nothing of it until he heard she went missing, he said. Then he called the police.

“It’s gut-wrenching to know that I can have my daughter out here and I go inside for a minute and she’s gone,” Mr. Riley said. “You just do not expect it from a town like this.”

The case baffled officials, who said they conducted more than 500 interviews in the course of the investigation and searched through farms and cornfields for answers. Investigators appealed to the public for help, creating a special website where people could leave tips. Ms. Tibbetts’s family even canvassed the Iowa State Fair with fliers, T-shirts and buttons, hoping to generate new leads.

Rob Tibbetts, Ms. Tibbetts’s father, told The Des Moines Register that he met with Vice President Mike Pence off-camera for about 20 minutes aboard Air Force Two last Wednesday, after Mr. Pence gave a speech in Des Moines promoting President Trump’s agenda.

Ahead of his remarks in Des Moines that day, Mr. Pence said, “I just want Mollie’s family to know: You’re on the hearts of every American, and we will continue to work and we will continue to pray for Mollie’s safe return.”

Crime Stoppers of Central Iowa had offered a $385,718 reward gathered from about 223 donors for any information leading to Ms. Tibbetts’s return.