**For the latest on the trial, visit wgntv.com/scholar.**
CHAMPAIGN, Ill. — Brendt Christensen, 29, was charged in the 2017 disappearance and death of a visiting Chinese scholar at the University of Illinois at Urbana-Champaign.
Yingying Zhang, 26, a visiting scholar doing research at the Department of Natural Resources and Environmental Sciences, went missing on June 9, 2017 in Champaign, and her body was never found.
Zhang was on her way to sign an apartment lease and was waiting for a bus around 2 p.m. June 9, 2017, when investigators said Christensen lured her into his car.
Surveillance video shows her speaking to the driver of a black Saturn Astra — the same type of car Christensen has — on the east side of Goodwin Avenue in Urbana before getting into the front passenger seat. That was the last time she was seen.
While the scholar’s body was never found, she is presumed dead.
WATCH: Surveillance video captures Yingying Zhang right before her disappearance. Note: Video is from 2017.
Over the course of several weeks after the student's disappearance, authorities began to investigate Christensen. During the investigation, his girlfriend wore a wire for the FBI. Those recordings are now at the center of the trial in Peoria.
Christensen was arrested on June 30 and later charged with kidnapping resulting in death. He pleaded not guilty.
If a jury convicts him, he will be the first federal defendant given capital punishment in Illinois in nearly 15 years. Illinois abolished capital punishment in 2011, but it is available under federal law.
Christensen was a Ph.D candidate in physics at the university and was an instructor. He had no criminal record. He was living with his now ex-wife Michelle Zortman at an off-campus apartment at the time of the incident.
Suspect's girlfriend wore wire for FBI
Christensen’s girlfriend — referred to only by the initials T.B. in the defense filing — secretly recorded him for days before his arrest. At the time, Christensen was also married to another woman.
One of the places where the girlfriend recorded Christensen was the June 29 vigil for Zhang’s family, friends and supporters amid the search for her. According to the Chicago Tribune, prosecutors said Christensen talked about how he held Zhang against her will and how she tried to fight back. They said he also described who would make the perfect victim.
Typically, agents want anyone wearing such a device to stay calm so that suspects aren’t tipped off that they’re being recorded. But citing government records, the defense filing describes how the girlfriend sent texts to agents supervising her, telling them that her “heart” was “pounding” and that she “went into shock and passed out while talking to” Christensen.
The defense discussed her state of mind in arguing that the presiding judge should exclude the recordings as trial evidence because, they say, the girlfriend didn’t agree to cooperate with the FBI voluntary.
The defendant’s lawyers are trying to paint the girlfriend as heavily-medicated, mentally unstable and an unreliable witness.
Bloody handprint found in Christensen's apartment
In February, prosecutors said that a bloody handprint was found in Christensen's apartment, but did not say whose hand it represented.
Prosecutors said a cadaver-sniffing dog detected traces of a dead body in the bathroom near the door and sink of the apartment. Other evidence includes the possible presence of blood on a bedroom wall and floor.
Christensen’s lawyers asked the judge to bar much of that evidence, saying that the sheriff’s department’s cadaver-sniffing dog, is unreliable because of inadequate training.
Defense lawyers also said initial indications of blood in some locations couldn’t be confirmed in subsequent tests. They argued some forensics techniques employed by investigators are error-prone and others simply signaled blood was present in the apartment, but couldn’t show definitively that the blood was Zhang’s.
Christensen visited walk to support Zhang's family in Urbana
Photos circulated online in July 2017 showing Christensen participating in the June 29 walk to support Zhang's family during the search for their daughter.
A CNN reporter captured a photo of him standing in the back of the rally outside the Krannert Performing Arts Center at the University of Illinois on June 29, 2017 — one day before the FBI arrested him.
Undercover police said they followed Christensen for almost two weeks before he was arrested. During the walk, the girlfriend was recording their conversations.
FBI rules out possible Salem sighting of Zhang
On July 12, 2017, WQAD reported that a possible sighting of Zhang in Salem was ruled out.
Earlier that same day, the news outlet said the FBI was investigating multiple tips from people who said they’ve seen Zhang in the southern Illinois town.
Police met with Zhang's parents to show them video of the woman who was apparently mistaken for their daughter, WQAD reported.
Lawyers for Christensen tried to delay the trial in order to investigate sightings of the scholar.
Christensen visited fetish websites with info on abduction fantasies
A federal complaint said that Christensen’s phone was used on April 19, 2017 to visit the FetLife.com forum, including to view threads titled “Perfect abduction fantasy” and “planning a kidnapping.”
FetLife describes itself as “the Social Network for the BDSM, Fetish & Kinky Community,” stressing in online policy statements that it is a place for consenting adults to trade advice and images of themselves, and to arrange to meet. As of 2017, it had more than 5 million registered members.
In early 2017, FetLife decided to prohibit hundreds of fetish categories after it was cited in a few criminal cases, including one in Australia, according to an online note to members from the founder.
Detailed policy guidelines on the site stress that any interaction online or in person with members must be between adults and consensual.
Zhang's family arrives in Peoria ahead of trial
Zhang's parents, Ronggao Zhang and Lifeng Ye, arrived from China on May 29 with their son ahead of the trial. The family said in a statement that they “want to be present on behalf of Yingying and follow the case closely.”
Her family also came to Illinois shortly after she went missing.
The Associated Press contributed to this report.