Zhang Ronggao (in blue T-shirt), father of missing Chinese scholar Zhang Yingying, arrives at the courtroom before an arraignment toward Brendt Christensen,who was indicted for kidnapping of Zhang Yingying in Urbana, Illinois, the United States, July 20, 2017. (Xinhua/Wang Ping)

CHICAGO, July 20 (Xinhua) -- Brendt Christensen, the accused kidnapper of Chinese scholar Zhang Yingying, pleaded not guilty to charges against him on Thursday during his arraignment at a federal court in Midwest U.S. state of Illinois.

The arraignment in federal courthouse in Urbana of Illinois lasted not more than five minutes, and Christensen broke his silence, speaking some time during the proceeding.

As expected, Christensen pleaded not guilty in his third appearance in less than three weeks in U.S. Magistrate Judge Eric Long's crowded courtroom.

In a statement, Christensen's attorney Anthony Bruno said: "he's demanded a jury trial and he plans to persist in his plea of not guilty."

Brendt Christensen's attorney Anthony Bruno speaks to reporters after the arraignment toward Christensen in Urbana, the United States, July 20, 2017. (Xinhua/Wang Ping)

Asked about the worldwide attention the case has received, Bruno said: "bad things happen everywhere. Nowhere else in the U.S. is a person from China more welcome."

Bruno said the case could go on a year or more.

U.S. lawyer Wang Zhidong, who has been offering legal support to the Zhang family on a voluntary basis, said outside the court, "this result is not unexpected and the case enters into another stage."

Christensen's next pretrial hearing was set for 2:45 p.m. on August 28, and his trial date is set for Sept. 12.

FBI officials also say they don't believe that Zhang is alive at this point. Law enforcement agencies are still searching for Zhang's location.

Zhang, a visiting scholar at the University of Illinois at Urbana-Champaign (UIUC), was last seen entering a black Saturn Astra car driven by 28-year-old Brendt Christensen on June 9.

Photo taken on July 20, 2017 shows the courthouse of United States District Court for the Central District of Illinois in Urbana, the United States.(Xinhua/Wang Ping)

Police arrested Christensen for kidnapping 26-year-old Zhang on June 30, but Zhang's location is still unknown.

The FBI believes Zhang is deceased, based on facts presented in court, court documents and other facts uncovered during the ongoing investigation.