UPDATE: An undocumented immigrant has been charged with the murder of a University of Iowa college student who was last seen during an evening jog over a month ago, authorities said on Tuesday.
Cristhian Bahena Rivera, 24, was charged with first-degree murder in the death of Mollie Tibbetts, 20, according to the Iowa Division of Criminal Investigation.
Officials announced the charge just hours after they discovered what they believed to be Tibbetts' body in a farm field east of her hometown of Brooklyn, Iowa.
"Our hearts go out to the Tibbetts family and to the Brooklyn community. It is a loss for all of us," Poweshiek County Sheriff Tom Kriegel said in a news release.
Investigators said they used surveillance video to track down Rivera. The video showed Tibbetts jogging in a rural area near her hometown of Brooklyn as well as Rivera's car.
“I can’t speak about the motive. I can just tell you that it seemed that he followed her, seemed to be drawn to her on that particular day, for whatever reason he chose to abduct her,” DCI special agent Rick Rahn told reporters at a news conference on Tuesday afternoon.
Rivera is originally from Mexico, according to Immigration and Customs Enforcement spokesman Shawn Neudauer.
A massive search had been underway for Tibbetts, who vanished on July 18 and whose disappearance sparked national attention.
Dozens of volunteers in the town of Brooklyn, Iowa, which has a population of about 1,500, had been searching fields around her house and the house where she was staying. Searches were also conducted by ground and air, and the use of dogs.
Crime Stoppers of Central Iowa offered a reward of nearly $400,000 for any tip that led to her safe return.
The surrounding area had been covered with missing person posters, T-shirts and billboards pleading for help in finding the missing woman.
Police were also scanning Tibbetts' digital footprint in an attempt to find her, Iowa Division of Criminal Investigation spokesman Mitch Mortvedt said last month. Tibbetts, an avid runner, often wore a Fitbit, according to her family.
Tibbetts' boyfriend, Dalton Jack, said he received a Snapchat message from her the night she disappeared after she would have returned from her run. She was reported missing the following day after she failed to show up for work.
Jack is not a suspect in the investigation. He was working a construction job about 100 miles northeast in Dubuque when Tibbetts went missing.
"She's not going to run off," Jack said in an interview earlier this month. "I try not to speculate on it too much because the only thing that comes into your head whenever you're not investigating all the facts is that something bad happened and you don't, I personally don't want to believe that."
Tibbetts was staying at Jack's home, where she was watching his dogs, at the time she went missing.
Iowa's two Republican senators, Sens. Chuck Grassley and Joni Ernst, in a joint statement said their hearts go out to the young woman’s family, and they said "too many Iowans have been lost at the hands of criminals who broke our immigration laws. We cannot allow these tragedies to continue."
President Donald Trump also mentioned the killing at a campaign-style rally in West Virginia Tuesday evening, calling Tibbetts an "incredible, beautiful young woman," and saying that the murder "should have never happened."
"The laws are so bad. The immigration laws are such a disgrace," Trump said.
PREVIOUS STORY: IOWA CITY, IA (AP) — Investigators believe they have found the body of Mollie Tibbetts, a University of Iowa student who has been missing for more than a month.
The 20-year-old woman was last seen July 18, jogging in her hometown of Brooklyn in central Iowa.
Greg Willey, the vice president of Crime Stoppers of Central Iowa, says a body found Tuesday is believed to be Tibbetts.
No information has been released about where the body was found.
Willey says a nearly $400,000 reward fund for her discovery will now become a reward for information leading to the capture of any suspects.