JETT BIRCHUM (in court): Cayley looked like she was tryin' to create space and kinda just get away.

ALESSANDRA CRANSHAW: And then what do you see him do?

JETT BIRCHUM: As she's tryin' to step away, I see him reach out his right arm and hook it around her shoulder and pull her in closer. And then turn and walk away.

Peter Van Sant: This is important testimony.

Christy Jack: It's important testimony because it's showing that she's being … being taken someplace against her will.

Defense attorney John Hunter hammers him on cross-examination.

Christy Jack: It immediately falls apart almost from the very first question.

In his questioning, Hunter confronts Birchum revealing how he initially misled investigators about what he had seen.

JOHN HUNTER (in court): You advised the police that you saw Mark physically pick her up and place her in his car, isn't that correct?

JETT BIRCHUM: Yes, sir.

JOHN HUNTER: And it differs from the testimony that you gave today, right?

JETT BIRCHUM: Yes, sir. … I did not see him put her in the car.

Birchum admits he exaggerated to police. But why? Prosecutors say he was worried about Cayley's safety and wanted to convince cops to search for her. Hunter then challenges Birchum regarding inconsistencies in his testimony to a grand jury about the timeline at the music festival.

JOHN HUNTER (in court): Would it surprise you to learn that the phone call you placed to Cayley Mandadi's phone was made at 7 o'clock?

JETT BIRCHUM: No, sir.

In an effort to undermine Birchum's credibility, he is asked about an unrelated drug charge.

JOHN HUNTER (in court): You were on probation at the time, were you not, Mr. Birchum?

JETT BIRCHUM: Correct.

In 47 minutes of brutal questioning, Birchum "takes the fifth" 30 times, with his lawyer by his side.

JETT BIRCHUM: … provided by the Fifth Amendment.

The damage was done.

Peter Van Sant: Tell me the impact of him saying over and over that he's taking the fifth?

John Hunter: The impact I think can't be understated. It's — it's a huge thing to see somebody do that.

Hunter has a star witness of his own — Dr. William Anderson, a forensic pathologist and former medical examiner who reviewed Cayley's autopsy and records for the defense

DR. WILLIAM ANDERSON (in court): So you look at the autopsy you're going to see—you're going to see what looked like bruises.

Anderson presents the crux of Hunter's case: that Cayley's bruising was caused in part by resuscitation efforts at the hospital, and the organ donation process.

Anderson goes a step further, pointing to a thin line in a photo of Cayley's skull.

DR. WILLIAM ANDERSON (in court, pointing to autopsy photo): Starting here we have this jagged line. So, like I said, it's like a crack in an eggshell, and that is a skull fracture.

A skull fracture, which Hunter says could indicate that Cayley's brain bleed was caused by a fall.

Peter Van Sant: She was in a car.

John Hunter: Well, she was in a car for portions of … that day. … Hematomas don't kill people instantaneously.

CHRISTY JACK: I don't think that you can overstate the importance of his testimony from a defense perspective. … It creates the impression that all of these injuries occurred by every other means, but Mark Howerton.

Once the defense rests, prosecutors bring the medical examiner back to challenge Dr. Anderson's testimony.

ALESSANDRA CRANSHAW: Is that a skull fracture?

DR. SUZANNA DANA: No, it's not.

Christy Jack: The faint line that Dr. Anderson was referring to came from a picture. … I didn't believe it. I thought it was reckless for him to have that opinion so definitively with only a picture.

The jurors must now make a momentous decision. Did Mark Howerton kill Cayley?