Mollie Tibbetts' accused killer pleads not guilty to murder charges

Cristhian Rivera, the illegal immigrant accused of killing Iowa college student Mollie Tibbetts, pleaded not guilty to murder charges at his Wednesday arraignment.

Rivera's trial is set to begin April 16 of next year.

Rivera, 24, was arrested and charged with first-degree murder on Aug. 21 after police searching a cornfield about 12 miles southeast of Brooklyn discovered the body of Tibbetts, a 20-year-old University of Iowa student.

Tibbetts was last seen jogging in Brooklyn on July 18 and the desperate efforts to find her drew widespread media attention.

Prosecutors allege Rivera abducted Tibbetts while she was out for an evening run, killed her and disposed of her body in the secluded location.

Authorities announced last month preliminary autopsy results from the state medical examiner's office showed Tibbetts was the victim of a homicide and died from "multiple sharp force injuries."

A criminal complaint alleges Rivera confessed to authorities during a lengthy interrogation, saying he drove his car to follow Tibbetts' jog, eventually got out on foot to talk to her and then chased after her. Rivera told investigators he panicked after Tibbetts threatened to use her cellphone to call police. He claims he blacked out at that point and later came to as he was unloading Tibbetts' bloody body from the trunk of a car, according to the complaint.

Mollie's father, Rob Tibbetts, in a eulogy at her funeral in late August, thanked the volunteers and law enforcement officers who joined in the search for his daughter. He also thanked the media, whom he credited with generating 400,000 tips about Mollie's potential whereabouts.

"Today, we need to turn the page," Tibbetts said. "We're at the end of a long ordeal, but we need to turn toward life — Mollie’s life. Because Mollie's nobody's victim."

Mollie's brother, Jake Tibbetts, described his older sister as someone who worked to bring together people with differences.

"You've seen how hard Mollie is working upstairs in heaven," Jake said during the funeral.

President Trump, in an interview at the time with "Fox & Friends," described Tibbetts as a "beautiful young girl" who was killed by a "horrible person that came in from Mexico, illegally here."

Investigators have said Rivera arrived to the U.S. illegally from Mexico at some point between 4 and 7 years ago and an immigration detainer was placed on him after his arrest.

In August, United States Citizenship and Immigration Services told Fox News "a search of records by USCIS revealed Rivera did not make any DACA requests nor were any grants given.

“We have found no record in our systems indicating he has any lawful immigration status,” the agency added.

DACA, or Deferred Action for Childhood Arrivals, was instituted during the Obama administration and allows some immigrants brought to the U.S. illegally as children to remain in the country.

A search of Iowa court records also revealed no previous criminal history for Rivera, and it's unclear whether he'd ever been subject to prior deportation proceedings.

Fox News’ Lucia I. Suarez Sang, Samuel Chamberlain and the Associated Press contributed to this report.