PEORIA, Ill. — A federal prosecutor on Wednesday told jurors in grisly detail that authorities believe a former University of Illinois doctoral student kidnapped a visiting scholar from China, and beat her to death with a baseball bat. Defense attorneys intent on sparing their client a possible death penalty then offered an exceptional response: He did it.

Opening statements began in the death-penalty trial of Brendt Christensen, a case which is being closely watched in China and by Chinese students across the U.S. Christensen is accused of posing as an undercover officer to lure 26-year-old Yingying Zhang into his car on June 9, 2017, as she headed to sign a lease off campus.

Brendt Christensen's mugshot. Macon County Sheriff's Office

Christensen, who is over 6-foot, took Zhang to his apartment where he raped, choked and stabbed her in his bedroom, as the 5-foot-4 Zhang tried to fight him off, prosecutor Eugene Miller said in his opening statement to jurors Wednesday. Christensen then dragged Zhang into his bathroom, and pummeled her in the head with the bat before decapitating her, Miller said.

With Zhang's father, a part-time trailer-truck driver from China, sitting just a few feet away on a courtroom bench, Miller also revealed for the first time that Christensen was captured on an FBI wiretap bragging that Zhang had been his 13th victim. But the prosecutor didn't offer additional details, nor did he say if authorities believed him. Miller appeared to broach the issue in order to demonstrate Christensen's quest to be known as a serial killer.

Yingying Zhang's parents Lifeng Ye and Ronggao Zhang and brother Zhengyang Zhang arrive at court for jury selection in the trial of Brendt Christensen in the killing of Yingying Zhang in Peoria, Illinois, on June 3, 2019. Kamil Krzacynski / AFP - Getty Images

It was not immediately clear if authorities were investigating Christensen's alleged claim. Prosecutors have said they won't comment on the trial while it's ongoing.

Christensen became obsessed with serial killers in the months before for he kidnapped Zhang, Miller said, adding that Christensen was engrossed by the novel "American Psycho" and was intent on slaying someone in order to fulfill a goal of infamy that he'd set for himself. Zhang, who had only been in Illinois for two months in what was her first experience living outside China, aspired to become a professor in her home country to help her working-class parents.

"While Yingying was on campus pursuing her dreams, he was on campus pursuing something dark — something evil," Miller said, standing at a podium in front of jurors.

Yingying Zhang University of Illinois Police Department

A federal judge moved the trial to Peoria in central Illinois after Christensen's lawyers said pretrial publicity would have made it impossible for the 29-year-old former physics student to get a fair trial in the Champaign area, where the 45,000-student university is located. The university has more than 5,000 Chinese students, among the largest such enrollments in the nation.

Zhang was unlucky to be in the wrong place at the wrong time, Miller told jurors, saying Christensen had determined on June 9 to kill someone that day and had been cruising in his car looking for a victim. Earlier, he approached a different young woman, also saying he was an undercover police officer. When he asked her to get into his car to answer some questions, she refused.

Prosecutors allege Christensen took advantage of Zhang's small stature and lack of English fluency after seeing her by a bus stop, pulling up and successfully talking her into his car. She had just missed a bus — even running after it — while she was on her way to sign the lease off campus in Champaign's sister city Urbana, 140 miles southwest of Chicago.

Later, the tall and muscular Christensen bound Zhang and got her into his apartment, where, Miller said, he raped Zhang in his bedroom and began stabbing her, blood splattering around the room. Christensen began trying to choke Zhang, Miller told jurors, citing a statement Christensen allegedly made to others.

"He choked her for 10 minutes," Miller said. "But she fought for her life."

After pulling her into the bathroom, Christensen picked up the bat and struck Zhang in the head as hard as he could, "splitting her head open," Miller said. Christensen cut off her head and disposed of the body, which has never been found.

Christensen rolled a pen through his fingers at a defense table as the prosecutor spoke. Zhang's dad, sitting about 15 feet away from Christensen, mostly looked straight ahead, unmoving, as the prosecutor offered details of his daughter's killing. Occasionally, he seemed to turn and look directly at Christensen.

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

When he first stepped up to the podium Christensen's lawyer, George Tesseff, told jurors he would begin his remarks with what he realized was an unusual admission for an attorney about his client: "Brendt Christensen killed Yingying Zhang," he said.

Without explaining in detail, Tesseff said Christensen was responsible because he "is on trial for his life," alluding to the possibility of a death sentence.

While the lawyer's admission was extraordinary it didn't necessarily contradict what the defense has said previously. While Christensen pleaded not guilty, the defense never argued law enforcement had the wrong man. The admission in court Wednesday was a signal that their sole objective was not to win a not-guilty verdict, but to persuade jurors not to vote to sentence Christensen to death.

Tesseff laid the groundwork in his opening statement, saying defense attorneys take issue with prosecutors' explanation of "how and why" Christensen did what he did. Tesseff portrayed Christensen's life as being in turmoil leading up to Zhang's disappearance, saying marital and drinking problems only made matters worse. Christensen was married at the time, but he had a girlfriend and his wife had a boyfriend in what the prosecutor earlier told jurors was their agreement to have "an open marriage" where they dated others. 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.

Christensen appeared to bow and shake his head slightly when his lawyer spoke of Christensen's life spinning out of control in 2016.

Tesseff told jurors they would see video of Christensen seeking help from U of I mental-health counselors for homicidal and suicidal thoughts.

He also mentioned a statement Christensen made about killing others, saying his client was clearly in a drunken stupor at the time and that there is no evidence he ever killed anyone else other than Zhang.

Christensen was arrested on June 30, 2017, his birthday, after his girlfriend wore a wire for the FBI in a bid to capture incriminating statements by Christensen. The girlfriend is expected to be the government's star witness.

Because Zhang's body was never found, the first government witnesses were called to help establish that she is, in fact, dead. Zhang's boyfriend, Xiaolin Hou, said he and Zhang planned to wed in October 2017. They talked almost every day even though he was in China, but the calls stopped after she went missing.

During his opening, Miller said Christensen's own words proved Zhang is dead. In a secret recording by the girlfriend, caught as Christensen attended a June 29 campus vigil for Zhang, he told his girlfriend the people were "there for me." Miller said.

Christensen added: "She's never going to be found. ... She's gone forever."

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