Lifeng Ye, the mother of slain University of Illinois scholar Yingying Zhang, cries out in grief as her husband Ronggao Zhang, far left, addresses the media after a jury found Brendt Christensen guilty of her murder Monday, June 24, 2019 outside the U.S. Federal Courthouse in Peoria, Ill. Consoling her is her son Zhengyang Zhang, far right, and family friend Dr. Kim Tee. (Matt Dayhoff/Journal Star via AP)

PEORIA, Ill. (AP) — Jurors deliberated less than 90 minutes before returning a guilty verdict Monday in the federal death-penalty trial of a former University of Illinois doctoral student who abducted a visiting Chinese scholar from a bus stop and killed her at his apartment.

Brendt Christensen didn't move or show any emotion as the judge read the jury's verdict — a swift conviction that was widely expected after defense attorneys acknowledged at trial Christensen killed 26-year-old Yingying Zhang in June 2017 and said they would focus all their energy on persuading jurors to spare his life.

Zhang's mother, Lifeng Ye, cried inconsolably by the courthouse steps shortly after the verdict as someone stroked her hair and tried to comfort her.

Ronggao Zhang thanked jurors for what he called "this first step toward justice" for his daughter. He was alluding to the death penalty stage at which the same jury must decide if Christensen should be put to death .

He has said previously that the 29-year-old Christensen — who prosecutors say raped, choked and stabbed Zhang before beating her with a baseball bat and decapitating her — deserved execution.

"We have missed Yingying tremendously," Ronggao Zhang said in Chinese, reading from a statement. "We still could not imagine how we will live the rest of our lives without her."

Zhang's body hasn't been found and her father said they still wish to "find Yingying and bring her home."

"We will not give up," he said.

Judge James Shadid set July 8 for the start of the penalty phase, a sort of mini-trial that could last several weeks. Illinois no longer has capital punishment, but Christensen could be sentenced to death because he was convicted in federal court.

Of the 45,000 students attending the University of Illinois in Champaign, more than 5,000 are Chinese students, which is among the largest such enrollment in the nation. Those students have closely followed developments from the trial, which is being held at U.S. District Court in Peoria.

Zhang had been in Illinois for just three months — her only time living outside China. The daughter of working-class parents, she aspired to become a professor in crop sciences to help her family financially. Friends and family described her as caring and fun-loving.

"The tragic truth is Yingying is gone," prosecutor Eugene Miller said during closing arguments earlier Monday. "There is only one person responsible — and he sits right there."

Christensen twisted and pulled at a rubber band at a nearby defense table as Miller spoke. Zhang's father sat on a front bench several feet away, listening to a Chinese interpretation of proceedings through a headset.

Miller said Christensen abducted a stranger who was "an object for him to fulfill his dark desire — to kill for the sake of killing."

When Zhang still lived in China, Christensen had already decided he would kill "a petite woman who could easily be disposed of," Miller said, adding that Zhang was "the ideal victim" to Christensen.

Christensen, posing as an undercover officer, lured Zhang into his car when she was running late to sign an apartment lease on June 9, 2017, Miller said. He told jurors the muscular Christensen likely forced the 5-foot-4 Zhang into a 6-foot-long duffel bag he bought online days before to carry her up to his apartment in Urbana, Champaign's sister city 140 miles (225 kilometers) southwest of Chicago, where he raped and killed her. Miller suggested Christensen then carried Zhang's remains out of the apartment in the same bag.

The defense ended the trial as they began it, repeating the admission that their client, in fact, killed Zhang. The admission took the suspense out of the jury deliberation, and made a guilty verdict all but certain. Legal experts say the risky strategy could also be a basis for an appeal by Christensen.

"It's Brendt's fault," Elisabeth Pollock, an attorney for Christensen, said about Zhang's death. She added that he was "someone who lost control ... who battled these dark thoughts." She said he lost that battle and that Zhang died as a result.

Pollock said prosecutors were, in some instances, asking jurors to infer things that can't be known from the existing evidence — including what Christensen did to Zhang before killing her.

When she added, "We are here because the government wants to take his life," prosecutors objected and the judge stopped her. Judge Shadid told jurors they were not yet in the penalty phase of the trial and the only issue now was the defendant's guilt or innocence.

Jurors heard evidence that Christensen boasted he killed 12 others before killing Zhang, starting when the Stevens Point, Wisconsin, native was 19 and still living in Wisconsin. He began his studies in Champaign at the university's prestigious doctoral program in physics in 2013.

Miller referred to Christensen's serial killer claim during opening statements but not in his closing, which lasted more than an hour. The FBI said it could not rule out that Christensen killed 12 others. But Pollock, who addressed jurors for less than 15 minutes, told jurors Monday there was no evidence that Christensen killed before.

Prosecutors said Zhang was in the wrong place at the wrong time and that Christensen, who had fantasized about killing, was determined to take someone's life that day and had cruised around in his car looking for a victim. They said he had approached a different young woman earlier posing as an officer, but she refused to get in the car.

Christensen and his girlfriend, Terra Bullis, attended a vigil for Zhang on June 29, during which Bullis wore an FBI wire and recorded him giving details about how he killed Zhang. As they were leaving the night of the vigil, Bullis said she'd rather not call a ride-sharing service, telling Christensen: "My version of safer is walking at night with a serial killer." He responded: "Yeah. That's me."

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Follow Michael Tarm on Twitter: https://twitter.com/mtarm

FILE - This file photo provided by the Macon County Sheriff's Office in Decatur, Ill., shows Brendt Christensen. Jurors on Monday, June 24, 2019 in Peoria, Ill., have convicted Christensen, a former University of Illinois doctoral student in the slaying of Yingying Zhang, a visiting scholar from China who was abducted at a bus stop as she headed to sign an off-campus apartment lease. The guilty verdict Monday was expected because Brendt Christensen's attorneys acknowledged from the start that he raped and stabbed Yingying Zhang in June 2017. (Macon County Sheriff's Office via AP, File)
FILE - This 2016 selfie provided by her family shows Yingying Zhang in a cap and gown for her graduate degree in environmental engineering from Peking University Shenzhen Graduate School. Jurors on Monday, June 24, 2019, in Peoria, Ill., have convicted Brendt Christensen, a former University of Illinois doctoral student in the slaying of Zhang, who was abducted at a bus stop as she headed to sign an off-campus apartment lease. Zhang's body has not been found. (Zhang Family Photo via AP, File)
Family members try to console Lifeng Ye, the mother of slain University of Illinois scholar Yingying Zhang, as they address the media after a jury found Brendt Christensen guilty of her murder Monday, June 24, 2019 outside the U.S. Federal Courthouse in Peoria, Illinois. (Matt Dayhoff/Journal Star via AP)
Lifeng Ye, the mother of slain University of Illinois scholar Yingying Zhang, cries out in grief as her husband Ronggao Zhang, far left, addresses the media after a jury found Brendt Christensen guilty of her murder Monday, June 24, 2019 outside the U.S. Federal Courthouse in Peoria, Ill. Consoling her is her son Zhengyang Zhang, far right, and family friend Dr. Kim Tee. (Terrence Antonio James/Chicago Tribune via AP)
Attorney Wang Zhidong, surrounded by family members of slain University of Illinois scholar Yingying Zhang, addresses the media after a jury found Brendt Christensen guilty of her murder Monday, June 24, 2019 outside the U.S. Federal Courthouse in Peoria, Illinois. (Matt Dayhoff/Journal Star via AP)
Lifeng Ye, left, and her son Zhengyang Zhang, right, the mother and brother of slain University of Illinois scholar Yingying Zhang, leave the U.S. Courthouse in Peoria, Ill., on Monday, June 24, 2019, after a federal jury found Brendt Christensen guilty of kidnapping and murdering Yingying Zhang. (Terrence Antonio James/Chicago Tribune via AP)
Members of the media crowd around the family of slain University of Illinois scholar Yingying Zhang to hear an address from attorney Wang Zhidong after a jury found Brendt Christensen guilty of her murder, Monday, June 24, 2019, in Peoria, Ill. (Matt Dayhoff/Journal Star via AP)