Mollie Tibbetts' Killer Pleads Not Guilty to Murder

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 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 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 of the state medical examination of 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 long interrogation, saying he drove his car to follow Tibbetts' jog, eventually got off to a good start. Rivera told investigators he panicked after Tibbetts. He claims that he is unloading Tibbetts' bloody body from the trunk of a car, according to the complaint.

Mollie's father, Rob Tibbetts, in a eulogy at his 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 to 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 from Mexico, illegally here."

Investigators have said Rivera arrived at 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 has not been successful.

"We have found no record in our systems of immigration status," the agency added.

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

A search for Iowa court records also reveals no previous criminal history for Rivera, and it 's unclear whether or not it has been subject to prior deportation proceedings.

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