PEORIA, Ill. (AP) - The FBI is investigating the claim by a former University of Illinois doctoral student that the visiting scholar from China he's charged with killing was his 13th victim, even though no evidence has been found to indicate whether he was telling the truth, an FBI agent testified Monday.
"We are continuing to investigate, and that's as far as we can go at this time," Agent Andrew Huckstadt said during Brendt Christensen's federal death-penalty trial.
He pointed out that not being able to corroborate the claim Christensen made to his girlfriend shortly after he allegedly killed Yingying Zhang in June 2017 is "not the same as saying it's completely impossible."
Prosecutor Eugene Miller claimed in opening remarks last week that 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. Christensen then dragged Zhang into his bathroom, and pummeled her in the head with the bat before decapitating her, Miller said.
The beginning of the second week of Christensen's trial began as the first week ended - with the focus on conversations between Christensen and his girlfriend that were secretly recorded, while authorities were conducting a massive manhunt for Zhang. Authorities say the woman agreed to be a confidential source for law enforcement shortly after Christensen posed as an undercover officer to lure 26-year-old Zhang into his car as she headed to sign a lease off campus, and kidnapped her.
On Friday, the federal jury listened to the recordings, hearing Christensen describe in gruesome detail how after he brought Zhang to his apartment, hit her in the head with a baseball bat, tried to choke her, stabbed her and finally decapitated her.
In the tape, Christensen never explicitly claimed that he killed 12 other people. However, he can be heard telling his girlfriend that she isn't in danger of becoming his next victim, explaining that she is too big. "It's about getting rid of 100 pounds versus 150 pounds," he said. "That's too much ... to get rid of."
Christensen was married at the time of the recordings, but he had a girlfriend and his wife had a boyfriend in what the prosecutor told jurors last week was their agreement to have "an open marriage" where they dated others.
Miller told jurors last week about Christensen's claim regarding additional victims but 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.
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.
On Monday, another witness, FBI Senior Forensic Examiner William O'Sullivan, talked about that fascination, telling jurors that in the weeks before Zhang disappeared, Christensen researched serial killers online.
O'Sullivan testified that Christensen went online to research decomposing bodies, downloaded photographs of bound and gagged women and read several posts about rape and kidnapping fantasies on a social media site for adults with alternative sexual interests. O'Sullivan said Christensen even exchanged posts with someone on the site in which he detailed how he was planning a sexual encounter that would include abducting her from her home, gagging her and stuffing her into a duffel bag and into his car. O'Sullivan also told jurors that Christensen watched online videos about knife sharpening.
Also testifying at the trial Monday was a police detective who told the jury that Christensen's demeanor and appearance changed dramatically when confronted with inconsistencies in his version of events.
University of Illinois Police Detective Eric Stiverson said Christensen began to tremble, break out in hives and appeared to hyperventilate under when he was confronted with inconsistencies in his version of events.
Christensen, now 29, never revealed in the recording what he did with Zhang's body, which has never been recovered. In one of the tapes, Christensen vowed never to tell anyone what he did with the body and said it will never be found.
Christensen is charged with kidnapping and killing her, which carries a possible federal death sentence. Last week, his attorneys, in attempt to prevent him from being executed, told jurors that Christensen had , in fact, killed Zhang.
The case is being closely watched in China and by Chinese students across the U.S.
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.
Also on Monday, an FBI forensic examiner testified that browsing history on Christensen's cell phone and that no relevant location data was recovered from it.