U.S. prosecutors argued Monday that an Illinois man who raped and murdered a Chinese graduate student two years ago should be executed, and called on her heartbroken fiancé and friends to tell the jury about the victim’s kind, optimistic nature.

A federal jury in Peoria, Illinois, found Brendt Christensen, 29, guilty last month of the abduction and murder of Zhang Yingying, a 26-year-old student at the University of Illinois at Urbana-Champaign. The jury is now in the penalty phase of the trial.

“This was not an ordinary crime,” James Nelson, a prosecutor in the U.S. Department of Justice’s capital case division, told the jury. “It was cold, cruel and calculated.”

Christensen’s lawyers have asked the jury to spare his life, saying he had long struggled with substance abuse and mental illness and had a family history of both.

The jury is being asked to decide between the death penalty and life in prison without the possibility of parole.

The victim’s fiancé, Xiaolin Hou, told the jury the couple met while undergraduates at Sun Yat-sen University in Guangzhou, China.

“She’s smart, she’s brave, she’s optimistic, she’s the best girl I ever met,” he said.

Videotaped testimony by Zhang’s college friends was also played to the jury. Christensen, dressed in grey trousers and a grey shirt, watched the videos with his lawyers.

U.S. prosecutors are seeking the death penalty under kidnapping laws.

Zhang was reported missing on June 9, 2017, two months after leaving southeastern China to study photosynthesis and crop production at the university. Her remains have not been found, but prosecutors said her DNA was matched to blood later found in three spots inside Christensen’s bedroom.

Investigators were led to Christensen through surveillance video captured in Urbana, 210 kilometers south of Chicago, that showed Zhang getting into a black car that was traced to Christensen.

Prosecutors said Christensen, a one-time master’s student at the university, took Zhang to his flat, where she fought for her life as he bludgeoned her with a baseball bat, raped her and stabbed her in the neck before cutting off her head.

Earlier in the trial in the court in Peoria, prosecutors said Christensen was fascinated with serial killers, including Ted Bundy, who murdered dozens of women during the 1970s and was put to death in 1989.

Details of the crime, including Zhang’s decapitation, were revealed by Christensen himself in conversations with his ex-girlfriend, who secretly recorded for them for the FBI, according to trial testimony.

(SD-Agencies)