A former University of Illinois doctoral student was convicted Monday of killing a visiting scholar from China after abducting her at a bus stop as she headed to sign an off-campus apartment lease.

Jurors deliberated less than 90 minutes at the federal death-penalty trial in Peoria, Ill.

The swift conviction was expected because Brendt Christensen’s attorneys acknowledged from the start that he raped and stabbed Yingying Zhang in June 2017.

Prosecutors said he beat her to death with a baseball bat and decapitated her.

Jurors found Christensen guilty of kidnapping resulting in death, which carries a possible death sentence. Prosecutors are expected in the penalty phase to focus on Christensen’s brutality, with the defense broaching mental health issues.

The judge has said there will be a break of a week or more before the penalty phase, a sort of mini-trial that could last several weeks.

Illinois no longer has capital punishment, but he could be sentenced to death because he was convicted in federal court.

The federal death-penalty case is the first in Illinois since the state struck capital punishment from its books on grounds that death-penalty processes were too error-prone. Some Illinois anti-death penalty activists criticized what they said was the government’s imposition of a death-penalty case on a non-death penalty state.

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The defense began the trial with the rare admission that their client killed Zhang, but said they said they disagreed with prosecutors over how and why. The surprising strategy was a bid to start immediately trying to persuade jurors to spare Christensen’s life.

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.

His lawyers said he made the claim about being a serial killer when he was drunk and that it was not true, but the FBI did not rule it out.

Christensen, now 29, lured Zhang into his car posing as an undercover officer when she was running late to sign the apartment lease on June 9, 2017. The muscular Christensen forced the 5-foot-4 Zhang into his apartment in Urbana, Champaign’s sister city 140 miles southwest of Chicago, where he raped and killed her.

Zhang was unlucky enough to be in the wrong place at the wrong time, prosecutors said, adding Christensen — who had fantasized about killing — determined to kill someone that day and had been cruising in his car looking for a victim. Earlier, he approached a different young woman posing as an officer, but she refused to get in the car.

He and his girlfriend, Terra Bullis, attended a vigil for Zhang on June 29, during which Bullis wore an FBI wire recording him detailing how he killed Zhang. As they left at night, she said she’d rather not call a ride-sharing service, telling him: “My version of safer is walking at night with a serial killer.” He responds: “Yeah. That’s me.”

Christensen was arrested on June 30, 2017, his birthday.

Christensen sought help from mental-health counselors at the school for homicidal and suicidal thoughts in the months before Zhang vanished, according to his lawyers, who said his life was spinning out of control. In his first few semesters as a doctoral student, Christensen was making straight As but by late 2016, was getting Fs in all his classes.

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There are more than 5,000 Chinese among the 45,000 students attending the University of Illinois in Champaign, one of the largest such enrollments in the nation.

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 Associated Press contributed to this report.