CHICAGO (CBS) — Brendt Chritsensen knew the FBI had been watching him.
Investigators had questioned the former University of Illinois student multiple times in the days following the disappearance of Chinese scholar YingYing Zhan. As FBI recordings reveal, he laughed with his girlfriend about the fact that investigators had been following and watching him in the Champaign-Urbana area.READ MORE: Chicago Weather: Winter Weather Advisory Issued For Illinois, Winter Storm Watch For Parts Of Indiana
“Like 10 different cars I’ve seen. That’s a new one,” he said, referring to a nearby car that he thought was an agent’s.
What he didn’t know is that his girlfriend was wearing an FBI recording device.
She had agreed to record their conversations for investigators. Prosecutors played the conversations Friday in the federal death penalty trial of Christensen, who is charged with kidnapping resulting in death.
Zhang disappeared June 9, 2017. Days later, Christensen is heard denying guilt in one recording.
“I’m not doing anything, so they can follow me all they want,” he said.
On June 29, after weeks of searching for Zhang on and around the University of Illinois campus, students gathered for a memorial walk and concert in her honor.
Christensen decided to attend. Prosecutors revealed photos and videos Friday showing him at the event with his girlfriend.
On the walk home, Christensen, who said he been drinking since the afternoon, began to discuss the crime in graphic and disturbing details, prosecutors say.
“I cut her clothes off and started doing stuff to her,” he said.
He described Zhang as “resilient.”
“I choked her for what must have been 10 minutes. Then I released her. Her breath. I couldn’t believe she was still alive,” he said.
Christensen, who was 27 at the time, told his girlfriend that he hit the 26-year-old Zhang in the head with a bat and stabbed her in the neck, but she still didn’t die.
“So I cut her head off, and then that was the end of it,” he said.
Prosecutors say the recording reveals that he bragged about killing 12 other people, but they admit there is no other evidence of more victims. He is only on trial for the death of Zhang, in which he is charged with kidnapping resulting in death.
“YingYing is the only person that has produced evidence that leads back to me. Number 13,” he said. “I’ve been at this since I was 19.”READ MORE: Bradley Police Officer Tyler Bailey Shot In The Line Of Duty Moved From ICU To Standard Care According To Statement From Family
Investigators say on June 9, Christensen lured Zhang into his car, kidnapped her, brought her back to his apartment, and committed the crime.
Zhang had just missed a bus ride and was on the way to tour an apartment off campus. She came to the university to work temporarily as a researcher and had dreams of becoming a professor.
During the trial, Christensen’s defense team has tried to paint him as a man with mental health and substance abuse issues who does not deserve the death penalty.
Prosecutors also played a video recording Friday from March 2017 showing Christensen speaking with a mental health counselor at the University of Illinois.
He said he had thoughts of hurting others and had an infatuation with Ted Bundy.
“I’ve always been interested in the bad guys,” he said.
Christensen is also heard discussing Bundy in the final recording from his girlfriend. He compared himself to the serial killer and said, “The last person to ever do anything at this level was Ted Bundy.”
The memorial walk was June 29. Christensen was arrested June 30th.
Zhang’s father kept his eyed closed throughout the recording. Christensen was mostly expressionless.
Sources say the family is hoping to locate Zhang’s remains for a proper burial in China.
Earlier in the day, prosecutors played a video of Christensen buying Drano and cleaning wipes at a Champaign Walmart. Investigators also say he bought a six foot duffel bag around the time of Zhang’s disappearance.
It’s not clear what he may have used the items for, and none of the evidence has revealed what may have happened to her remains.
Illinois abolished the death penalty in 2011, but federal authorities can step in and investigate exceptional crimes as death penalty cases even in non-death penalty states.
If convicted, the jury will partake in a separate process to decide whether Christensen should be executed.
The trial continues next week.MORE NEWS: Cook County Reopens Third Vaccination Site In A Week In Effort To Get More Residents Vaccinated