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UPDATE, 6:10 p.m.:

PEORIA — Brendt Christensen's ex-girlfriend, Terra Bullis, just finished her first day of testimony. When she walked to the stand, Christensen avoided looking at her and instead just stared straight ahead.

Bullis said her first date with him was in April 2017 at a cafe and bookshop. He was "whimsical," she said: "We chatted, walked around the bookshop." He was "very flirtatious. He seemed kind, courteous, amicable."

They were in a dominant-submissive relationship, she said. She was the submissive, and would clean the bathroom and kitchen for him, because she said he did not like to clean bathrooms.

She encouraged him to quit drinking after she found out his wife wanted him to.

Bullis said he ordered her to read "American Psycho" after she watched the film version and recalled him saying the main character was an attractive man and very intelligent. She said he talked about serial killers in the context of people who are remembered in history, and mentioned Ted Bundy and Adolf Hitler.

On June 9, 2017, Bullis texted Christensen that she had casual sex, even though she normally doesn't.

"You don't do the anything casual thing," Christensen responded. "From breathing to fine dining ... to murder."

"I didn't really know what to think," Bullis said about that text.

On June 16, she agreed to wear a wire for the FBI.

"I was emotionally attached to this person and wanted to know if they had done anything or not," she said. Wearing the wire "would be able to inform both myself and potentially law enforcement."

The FBI furnished her with two recording devices — a coffee mug and a small device about the size of a Post-It Note. She said she usually used the small device because it was easy to hide.

Over time, she said he spoke more during their conversations, and she would play up her submissive role, being confused and asking lots of questions.

On June 17, when he told her that he used a large duffel bag to transport a large present, his story didn't make sense to her, she said.

That same day, Christensen told Bullis that authorities found blood on his baseball bat and suggested it may have come from her face. In court Wednesday, she said this "would not be possible" as she has two blood disorders that prevents her blood from clotting properly.

"I was scared," she said. "I wanted to know why he was lying."

On June 19, Christensen told her he wanted to tell her more about what happened but couldn't. That same day, he said his wife had returned to their apartment but would not sleep in bed with him, instead sleeping on the floor in the computer room.

On June 23, he texted Bullis that "I was the one who picked that girl up. I dropped her off shortly after. I didn't do anything wrong." He said he was worried that police would get desperate and frame him.

Bullis said Wednesday that she felt conflicted.

"When I care about someone, I truly care about them," she said. "But I also cared about this missing person."

Bullis will continue testifying Thursday.

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UPDATE, 3 p.m.:

PEORIA — FBI biologist Amanda Bakker testified Wednesday afternoon about the blood and DNA stains found at Christensen's apartment. Among the highlights:

— She compared several samples to Ms. Zhang's DNA found on her toothbrush.

— One swab on a mattress had a presumptive test for blood that wasn't confirmed, and DNA with a likelihood factor of 1 in 44 sextillion that it was not a random person's and came from Ms. Zhang.

— Another mattress swab did not detect and had a DNA likelihood factor of 1 in 1.4 quintillion.

— A third mattress swab came back with blood presumptive, but not confirmed and a DNA likelihood factor of 1 in 3,000.

— A swab of a baseball bat came back with no blood detected and a DNA likelihood factor of 1 in 33 octillion.

— A carpet sample from under the bed came back with blood identified but no DNA from the usual method of extraction, so it was extracted manually and the likelihood factor returned was 1 in 97 octillion.

— Drywall behind bed came back with blood presumptive, but not confirmed and a DNA likelihood factor of 1 in 33 octilion.

— A swab of the baseboard under the bed came back with blood identified but DNA inconclusive.

— A tack strip came back with blood identified and a DNA likelihood factor of 1 in 1.4 billion.

— Tests on the Saturn Astra came back with no blood and DNA located, but not Ms. Zhang's.

— Tests of the bathroom came back with no blood, a presumptive positive for blood in the bathroom sink trap, but not confirmed, and DNA found, but not Ms. Zhang's.

— A swab of the carpet in the living room came back with no blood.

During cross-examination, defense attorney Elisabeth Pollock noted that only a third of the items sent to the lab were tested, including clothing and towels that came back with no blood on them, and two-thirds of items weren't tested, including knives, scissors and needles. Bakker said she chose what to test in part based on talking with investigators.

* * * * *

PEORIA — Last week, the jury heard a nearly hourlong interrogation of Brendt Christensen at the Champaign FBI office, where he starts to change his story about what he was doing the afternoon Yingying Zhang disappeared six days earlier.

That video was released to the public yesterday, and about 18 minutes in, University of Illinois police Detective Eric Stiverson puts pressure on Christensen, letting him know they have surveillance footage of him driving around campus and that they know he wasn't at home playing video games.

Christensen pauses and his voice changes, and he then changes his story, admitting that he was driving around campus and picked up an Asian woman with broken English, but dropped her off a couple blocks away.

"Maybe I'm getting my days mixed up, then," Christensen said. "I thought I drove around Saturday. I did pick a girl up."

When this happened, Stiverson said Christensen was trembling, hands in his lap, eyes darting left to right, and his breathing changed.

Later, Stiverson said it was like Christensen was hyperventilating. He was very pale and appeared to break out in hives, with red blotchy spots on his neck and face.

The prosecution believes he took Ms. Zhang back to his apartment and killed her, and today, an FBI biologist is expected to testify about the blood and DNA found at the apartment.