Montezuma, IA – The body of missing college student Mollie Tibbetts was found on Tuesday morning, and the authorities announced the arrest of an illegal immigrant for her murder at a press conference on Tuesday afternoon.

Tibbetts, 20, was last seen on the evening of July 18 when she went jogging in her hometown of Brooklyn.

She was staying at her boyfriend’s house, dogsitting, and she texted her mother that night and sent a Snapchat to her boyfriend, but she hadn’t been heard from since.

Her family contacted the police after she failed to show up at work on July 19, and wasn’t answering her phone.

A massive search effort and a $400,000 reward for information about the missing University of Iowa coed have dominated headlines for 34 days as authorities narrowed their search for Tibbetts to five primary locations, The Washington Post reported.

Those areas were a car wash, a truck stop, two farms, and Tibbetts’ boyfriend’s home.

Detectives received more than 4,000 leads from the public and interviewed 1,500 people during the investigation, police said.

Iowa Division of Criminal Investigation Special Agent in Charge Rick Rahn announced at the press conference that a body believed to be Tibbetts had been found on Aug. 21, but said the identity had not yet been confirmed.

Agent Rahn said authorities had arrested 24-year-old Cristhian Bahena Rivera and charged him with first-degree murder in the death of Tibbetts.

He also said Homeland Security Operations had confirmed that Rivera was an illegal alien.

The more-than-a-month-long search for the missing woman came to a head a week before Rivera’s arrest, when someone who lived along the route Tibbetts was believed to have been running came forward with surveillance video that showed the young woman jogging by on the night she disappeared, Agent Rahn said.

He said investigators spent more than 100 hours scouring the video and constructing a timeline of the incident.

Through that security footage, investigators were able to identify a black Chevy Malibu that belonged to Rivera, and they were able to determine that he was following Tibbetts. Her “digital footprint” left by her Fitbit and her cell phone also aided police in finding her killer, the agent said.

Agent Rahn said they were able to track Rivera’s vehicle and find Tibbetts running in the video on 385th Street.

He said they brought Rivera in for a lengthy interview on Aug. 20, and he readily admitted that he saw Tibbetts running and said he parked his car and got out so he could run alongside her, the agent told reporters.

Rivera told detectives that Tibbetts grabbed her phone and told him to leave her alone or she’d call the police. He told police that he became angry and chased her down, and then he claimed to have blacked out and didn’t remember what happened, Agent Rahn said.

The illegal immigrant, whom authorities said had been living in rural Poweshiek County for four to seven years, told police that his blackout ended near where they found Tibbett’s body at 460th Street.

He told police he did a u-turn and drove back into the entrance of a cornfield.

Rivera said that when his blackout ended, he saw an earbud in his lap and realized he had put Tibbetts in his trunk, according to an arrest affidavit filed with the Powesheik County Clerk of Courts.

When he got to the field, he got out of his car and went around to the back of the car to pull Tibbetts’ body out of the trunk.

Rivera told detectives that was when he noticed blood on the side of her head, according to the affidavit.

He told police he put Tibbetts over his shoulder and carried her body about 20 meters into the cornfield, where he dropped her and camouflaged her with corn stalks.

Rivera was able to describe what Tibbetts had been wearing and other details specific to the area where the young woman’s body was found, according to The Gazette.

An autopsy will be performed to determine Tibbetts’ exact cause of death, Agent Rahn said.

Rivera was held at the Powesheik County Jail on a $1 million bond. His case will be prosecuted by the Iowa Attorney General’s Area Prosecutors Team, the agent said.

If convicted, the murder charge carries a mandatory life sentence without possibility of parole for Rivera, according to The Gazette.