Officials say the accused then checked the boot of his vehicle, where he saw Ms Tibbetts' body wearing exercise clothing and with blood on both sides of her head.
Officials say Rivera was residing in the area illegally for at least four years.
They watched the footage for hours before they could spot Tibbetts, said Rick Rahn, a special agent in charge at the Iowa Division of Criminal Investigation.
"After we got done interviewing Mr. Rivera, he led us to her location".
Rivera sat stone-faced through much of the hearing, wearing a striped jail jumpsuit, handcuffs and speaking only briefly through a Spanish-speaking interpreter. After more than a month of searching, investigators located her body in a farm field in rural Poweshiek County on Tuesday, Aug. 21.
The statement adds, "We know that many of you will join us as we continue to carry Mollie in our hearts forever". He told police that he blacked out and that when he came to, the girl's body was in the trunk of his vehicle.
The Tibbetts family is specifically asking that her murder not become political, but it is already growing as a Republican campaign issue in 2018.
"This is a small community", Mortvedt said. Beyond that I'm not sure what he was doing.
Roughly a week ago, the resident handed over the tape, which Rahn said authorities pored over for hours.
In court records released Wednesday, Rivera's lawyer declared that "the Government knows Cristhian has legal status" and wrote that "Cristhian has complied with his documented status since arriving in the U.S.A.as a minor". According to Rahn, prosecutors with the Iowa Attorney General's Office will prosecute the case. "We have cooperated fully with their investigation". Investigators in Iowa said that after weeks of police work and grassroots action-putting Mollie's face on shirts and yard signs, maintaining a website dedicated to the search effort, relaying thousands of tips to authorities-the big break in the case came in the form of surveillance footage caught by a neighbor's security camera.
"They are not the same systems and we apologize for any confusion this caused with our earlier statement", Land said. Mollie was an awesome young woman and we are praying for her parents, brothers & friends in this time of unimaginable grief. He didn't seem to want to talk about her, just changed the subject. "So we are saddened for the family".
The manager of the dairy farm that employed the immigrant from Mexico expressed the shock he felt after learning that Rivera had been accused of killing the 20-year-old college sophomore. "Our heart goes out to the family and friends of Mollie Tibbetts".
"Mollie Tibbetts, an incredible young woman, is now permanently separated from her family".
His attorney, Richards, lashed out at President Donald Trump for publicly declaring his client guilty at a rally Tuesday night in which he called the nation's immigration system a disgrace. "We are angry that a broken immigration system allowed a predator like this to live in our community, and we will do all we can bring justice to Mollie's killer".