Jurors deliberated for less than 90 minutes before returning a guilty verdict on Monday at the federal death-penalty trial of a former University of Illinois doctoral student who killed a visiting scholar from China after abducting her at a bus stop as she went to sign an off-campus flat lease. The swift conviction was expected because Brendt Christensen’s lawyers acknowledged from the start that he raped and stabbed Zhang Yingying in June 2017. Prosecutors say he beat her to death with a baseball bat and decapitated her. 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 Christensen could be sentenced to death because he was convicted in federal court. There are more than 5,000 Chinese students of the 45,000 attending the University of Illinois in Champaign, among the largest such enrolments in the nation. They have closely followed developments from the trial at US 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. Christensen’s lawyers 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 their client’s life. Elisabeth Pollock, a lawyer for Christensen, said her client was “someone who lost control … who battled these dark thoughts”. She was an object for him to fulfil his dark desire – to kill for the sake of killing Prosecutor Eugene Miller When she added, “we are here because the government wants to take his life”, the prosecution objected and Judge James Shadid stopped her. He 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. Prosecutor Eugene Miller referred to the defence strategy of admitting Christensen killed Zhang, saying he was as surprised as anyone by the admission from the outset of the trial. He asked the question many jurors were likely asking themselves: why sit through eight full days of evidence if defence lawyers say their client did it? Because, Miller explained, “lawyers’ statements aren’t evidence” and the burden remained on prosecutors to prove Christensen did what they alleged he did. FBI investigates claims that Chinese scholar was accused’s 13th victim Miller also told jurors that Christensen abducted a stranger from a street near campus, someone he did not view as human. “She was an object for him to fulfil his dark desire – to kill for the sake of killing,” he said. “The tragic truth is Yingying is gone,” Miller told jurors as a photo of a smiling Zhang was displayed on a courtroom monitor. “There is only one person responsible – and he sits right there.” 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 programme 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. ‘Give my daughter back’: trial begins for Chinese scholar’s alleged killer Christensen, now 29, lured Zhang into his car on posing as an undercover officer when she was running late to sign the lease on June 9, 2017. The muscular Christensen forced Zhang into his flat in Urbana, Champaign’s sister city 225km (140 miles) southwest of Chicago, where he raped and killed her. Zhang was unlucky to be in the wrong place at the wrong time, prosecutors said, saying Christensen – who had fantasised 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 detail how he killed Zhang. As they left at night, she said she would 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, his birthday. 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 defence broaching mental health issues. Christensen sought help from mental-health counsellors at the school for his 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.