The search for Mollie Tibbets has come to a tragic end.

Police confirmed Tuesday they found the 20-year-old University of Iowa student's body after a five-week search. Tibbetts went missing on July 18 after going for a jog near Brooklyn, Iowa.

Cristhian Rivera, age 24, has been charged with first degree murder in the case. Police confirmed during a press conference Tuesday that he is an immigrant who is in the country illegally.

"We have confirmed with Homeland Security Investigations that he is and illegal alien and has been in this area for 4 to 7 years," Rick Rahn, special agent with the Iowa Division of Criminal Investigation, said at the press conference. "We first approached Mr. Rivera yesterday... There was no fight or struggle of any kind."

According to a charging documents , Rivera told investigators that he ran next to Tibbetts until she threatened to call the police and tried to run away. Rivera said he chased her and blacked out. He said he came to, realized that he had killed her and put her body in the trunk of his car, according to the documents. Rivera's bail was set at $1 million.

Police were led to Rivera as a suspect after they noticed security cameras at a house close to where Tibbetts was last seen. The owner of the house gave them access to the tapes and it provided enough evidence for the police to single out the suspect and detain him.

"The video was critical," Rahn said at the press conference. "Through that we were able to identify a vehicle that we believed belonged to Mr. Rivera. From that we were able to track his pattern and routes he took. We were also able to find Mollie running on this video and we were able to determine that he was one of the last to have seen Mollie running."

Rahn said that while they have not confirmed the identity of the body, they are convinced it is Tibbetts. The body was found in a cornfield Tuesday morning, with corn stalks "placed on top of her." The clothes are similar to what Tibbetts was last seen wearing.

An autopsy is scheduled for tomorrow, but Rahn said that it would take authorities four to six weeks to receive the final results.

The discovery of her body wraps up a highly publicized investigation. Authorities were tight lipped throughout the search, offering few details about possible leads. I owa police had up to 40 investigators working on the case with the reward for her safe return reaching up to $300,000.

Robert Tibbetts, Mollies father, said as recently as two-weeks ago that he believed his daughter was alive in an appearance on Fox News show Shepard Smith Reporting and pleaded with her suspected kidnapper to “Let Mollie go and turn yourself in.”

Last week investigators narrowed the search for Tibbetts to five locations near Brooklyn, including a TravelCenters of America truck stop and D&M Car Wash in Brooklyn.