(BROOKLYN, Iowa) -- Slain jogger Mollie Tibbetts and her alleged killer lived in the same rural Iowa town but it’s unclear whether they knew each other, investigators say.
Either way, "there was something that drew him to her," Mitch Mortvedt of the Iowa Division of Criminal Investigation told ABC News Wednesday.
Tibbetts, a 20-year-old rising sophomore at the University of Iowa, disappeared the evening of July 18 while jogging in the rural farming town of Brooklyn, a close-knit community of about 1,500 residents.
"Our hearts are broken," her family said in a statement. "We thank all of those from around the world who have sent their thoughts and prayers for our girl. We know that many of you will join us as we continue to carry Mollie in our hearts forever."
The college student's body was found in a farm field on Tuesday.
A first-degree murder charge was filed Tuesday against 24-year-old Cristhian Rivera, an undocumented immigrant, Rick Rahn of the Iowa Division of Criminal Investigation said. An immigration hold was also filed against Rivera.
He made an initial court appearance on Wednesday and is due to return to court on Aug. 31. Rivera has not entered a plea. When asked if he had anything to say, Rivera, through an interpreter, said "no."
Bond for Rivera was set at $5 million, cash only.
After Tibbetts vanished July 18, and her disappearance turned from days into weeks, federal and state investigators joined the search in the small town.
"Ultimately, what led us to Mr. Rivera was surveillance video from a residence here in the community of Brooklyn," Mortvedt said.
The video was found late last week, Mortvedt said, and "investigators went through the video and it took hours and hours and hours, frame by frame ... and eventually saw Mollie."
The video showed Tibbetts jogging and Rivera's car going by, officials said, and Rivera was tracked down by investigators Monday.
In an interview, Rivera told authorities he saw Tibbetts running, got out of his car and ran alongside of her, Rahn said.
Rivera said Tibbetts grabbed her phone and said, "I'm gonna call the police," according to an arrest affidavit.
Rivera told authorities he then panicked, got mad and "blocked" his "memory," and didn't remember anything after that until he reached an intersection, according to the affidavit.
Rivera said he then drove to a field entrance and into a cornfield driveway, before realizing he had Tibbetts in the trunk, the affidavit said.
Rivera said he went to get the young woman out of the trunk and saw blood on the side of her head, according to the affidavit.
Rivera then said he dragged the college student from his car to a secluded part of a cornfield and left her in corn leaves, face-up, the arrest affidavit stated.
Rivera led authorities to Tibbetts' body, according to Rahn.
An autopsy will be performed Wednesday.
"A tragic end," Mortvedt told ABC News. "All of us were hoping for a much better outcome for Mollie and her family."
"It's every parents worst nightmare," family friend Linda Safir told ABC station KGO in San Francisco.
"So sad, so wrong," Safir said. "She had so much to give."
"Mollie was a sweet girl," added Katie Murphy, principal at the Corpus Christi School where Tibbetts was a former student. "The best gift we can give is to be a little like Mollie today."
Copyright © 2018, ABC Radio. All rights reserved.