Cayley Mandadi, 19, was a sophomore at Trinity University when she was brought to a Texas hospital on Oct. 29, 2017. She was nearly naked, bruised and not breathing. Her sometime boyfriend Mark Howerton told doctors they'd taken ecstasy at a music festival and she passed out after consensual sex in his car. She died at the hospital.

In February 2018, authorities charged Howerton with Mandadi's murder, alleging her cause of death was blunt force trauma to the head. A year later, Howerton's trial ended with a hung jury.

A new trial was set for 2023. Mandadi's mother Alison Steele and stepfather Lawrence Baitland believed for the second trial jurors needed more information about what happened inside Howerton's car. Steele, a scientist, and Baitland, a NASA engineer, launched their own investigation.

"I needed to be able to show the jury what happened to Cayley," Baitland told "48 Hours" correspondent Peter Van Sant.

Using autopsy photos and consulting with experts, they developed a theory.

Would the couple's investigation change the course of the second trial?

CAYLEY MANDADI'S FINAL HOURS

Cayley Mandadi and Taylor Clement, best friends since ninth grade, had a streak – Snapchatting every morning.

Anonymous Source: Every single day. … She was much more of a morning person. So I would get mine first thing in the morning.

But on Monday morning, Oct. 30, 2017, there was no word from Cayley.

Anonymous Source: I didn't get a Snapchat at 8 o'clock in the morning, like I usually do. … That's actually how I knew something was really wrong.

Both good students, they bonded in science class. Clement says she was instantly drawn to Cayley.

Anonymous Source: She had like, a really infectious smile and the big eyes and like, the loving heart.

The two separated to go to different colleges. That October morning, Cayley was on Clement's mind.

Anonymous Source: As I'm working in the library, it's in the back of my head, like, I haven't heard from her.

Clement didn't know it, but just hours earlier, Cayley's mother Alison Steele and stepfather Lawrence Baitland were awakened at 4 a.m. with horrifying news.

Anonymous Source: "Your daughter's been involved in some incident, and she has been life-flighted to Kyle, Texas."

They raced from their home in Houston to the hospital, praying Cayley was OK.

Anonymous Source: What was it like when you entered that room? What did you see?

Anonymous Source: I saw my daughter's body smashed.

Tragic Loss of Cayley

Lawrence Baitland: I could see that she was on a ventilator … and my heart just stopped. And I knew that it was bad.

Within hours, Cayley's parents were told there was no hope for recovery. Their daughter, just 19 years old, once so full of life, was soon declared brain dead. Baitland and Steele want the world to know what happened to her.

Alison Steele: All that potential had been destroyed. And not knowing how it happened. Or how it was even possible.

They invited Cayley's friends to see her one last time. Clement sat with Steele as she held Cayley's hand and prayed.

Taylor Clement: I remember her repeating over and over, "this has to be for something, this has to be for something."

Cayley had previously requested that her organs be donated to help others. As she was taken to surgery for that procedure, her parents said goodbye.

Alison Steele: It was very emotional. … But, of course, we didn't want to let her go. But this is what had to be.

Just days before, things seemed to be going well for Cayley. A sophomore communications major at Trinity University in San Antonio, she had joined a sorority and was a cheerleader. And she'd met a boy.

Alison Steele: Cayley at the time was very much in love with the only serious boyfriend she had ever had. His name was Jett Birchum.

Birchum was a Trinity football player and fraternity brother. Cayley dated him freshman year, but they broke up.

Alison Steele: What she told me was, "I don't know that he wants a serious relationship." And she did.

Taylor Clement: I think that part of her life got very murky for her very fast.

There was another man in Cayley's life. Mark Howerton was 22 years old and had been a star high school baseball player.

Howerton lived in Houston but was often on Trinity's campus visiting friends. That's where he met Cayley.

John Hunter: I think that they're both very beautiful people and I think that that was the primary attraction.

John Hunter is Howerton's lawyer.

John Hunter: I think that there were problems with her relationship with Jett. … And Mark was offering an alternative to that.

Both Jett and Mark knew Cayley was seeing the other man and neither, friends say, liked the competition. Then, just one month into this new relationship, Mark Howerton rushes Cayley to a small rural hospital in Luling, Texas.

Police Interview Reveals Disturbing Details in Cayley's Case

During the investigation into the case of Cayley's assault, police officers interviewed Mark Howerton in the hospital chapel. The entire conversation was captured on the officer's bodycam.

DEPUTY CALENTINE (to Howerton/bodycam video): So tell me, where were you and Cayley at today?

According to Howerton's statement, he and Cayley attended the Mala Luna Music Festival, where they consumed alcohol and MDMA, also known as Molly or ecstasy.

Christy Jack, an attorney based in Fort Worth, reviewed the case files and noted a concerning incident at the music festival.

Christy Jack: They encountered Jett Birchum and an argument ensued.

Howerton claimed that after 4 p.m., he and Cayley left the festival in his Mercedes, still arguing about Cayley's lingering feelings for Jett.

MARK HOWERTON (police interview): I was trying to make her understand... You need to get over this guy. He's not worth your time. Your friends are fake... I was just trying to get through to her...

Howerton stated that they then stopped in a parking lot where they engaged in consensual rough sex.

MARK HOWERTON (police interview): We were having sex. I choked her. But it wasn't like I was killing her. It wasn't -- it wasn't like that.

According to Howerton, the sexual encounter involved choking but was consensual.

During a police interview, Mark Howerton claimed that the encounter was "500 percent consensual." He also stated that after they had sex, she continued to talk to him for several minutes before feeling unwell and passing out.

Hours later, while they were on the road, Cayley stopped breathing. Howerton attempted to resuscitate her but was unsuccessful. They then saw a sign indicating a hospital at the next exit and pulled off.

Emergency medical workers at the hospital noted that Cayley was in bad shape upon arrival. She was nearly naked, bruised, and had no pulse.

A paramedic or nurse at the hospital confirmed that the bruises were already present when Cayley arrived. Howerton explained that she bruises easily and often falls over when she is drunk.

Police Interviewed Howerton, Autopsy Report Reveals Homicide

Police interviewed Howerton several times, but he was not charged with any crime related to Cayley's death. Then, three months later, her autopsy report was released. The medical examiner ruled that Cayley had died from blunt force face and head trauma; it was ruled a homicide. Mark Howerton was charged with murder. He pleaded not guilty and was released on bail.

John Hunter: There were large amounts of drugs taken over the course of this weekend. Mr. Howerton brought the deceased to a hospital, which is something you don't typically see.

Peter Van Sant: Murderers don't usually do that.

John Hunter: No.

John Hunter: The idea that it was open and shut is a mistake.

As the trial begins, John Hunter says he has evidence that will surprise the jury.

MARK HOWERTON GOES ON TRIAL FOR THE MURDER OF CAYLEY MANDADI

In December 2019, two years after Cayley Mandadi's disturbing demise, Mark Howerton is finally brought to trial for allegedly kidnapping, assaulting and murdering her.

JUDGE: How do you plead, Mr. Howerton.

MARK HOWERTON: Not guilty, your honor.

Peter Van Sant: What was it like to see Mark Howerton in the courtroom?

Alison Steele: Like everybody else, I'd try not to look at him too much.

The trial begins with prosecutor Alessandra Cranshaw's opening statement.

ALESSANDRA CRANSHAW (in court): I think the best way to tell this story … is to start where Cayley Mandadi's life ended. And that's in the car of this defendant.

Prosecutors claim that Howerton forcefully took Cayley from the Mala Luna Music Festival to his car. He then drove her to a parking lot where he sexually assaulted and beat her, resulting in a fatal brain bleed.

A defense attorney, John Hunter, challenges the prosecution's case in his opening statement.

John Hunter argues that Mark Howerton is not responsible for Cayley's death.

John Hunter points out that there were no eyewitnesses to what happened between Mark Howerton and Cayley Mandadi on the evening of the 29th.

The state presents paramedic Sharyl Lane as its first witness, who describes a disturbing scene inside Howerton's car.

John Hunter: The physician who treated Cayley at the Luling hospital believed it was a drug overdose.

Peter Van Sant: Wasn't that because Mark had told them he thought she had overdosed?

John Hunter: Yes, that's correct. But the symptoms she showed were consistent with a drug overdose.

Peter Van Sant: So, was she beaten or not?

John Hunter: No.

Hunter argues that the bruises on Cayley's body were a result of the resuscitation efforts performed at the hospital.

John Hunter: By the time the sexual assault nurse photographed her, she had already been resuscitated multiple times. She had undergone various medical procedures and treatments at the hospital.

While the medical team fought to save Cayley's life, the police interviewed and photographed Mark Howerton. Police officer Chris Adams noticed something unusual during the process.

OFFICER CHRIS ADAMS: When I was taking photographs of him, I noticed that the tops of both of his hands were red.

DAVID LUNAN | Prosecutor: Do they look unusually red to you?

OFFICER CHRIS ADAMS: Yes, sir.

DAVID LUNAN: Unusually red?

OFFICER CHRIS ADAMS: Yes, sir.

Evidence, investigators believe, that Howerton did hit Cayley.

DEPUTY CALENTINE (to Howerton on bodycam): Those actually do look like they have scabs already on them.

The Mark Howerton arrested after Cayley's death was an enormously muscled, intimidating figure. Cayley's friends say he used steroids.

Christy Jack: … even in such a confined space. … it would've been relatively easy for him to cause that kind of damage to her head.

Howerton initially cooperated with investigators, allowing police to search his Mercedes, where they found a gun and marijuana.

John Hunter: If he was worried about himself, he would have told the police to get a warrant.

Instead, Hunter says, Howerton was much more concerned about Cayley.

MARK HOWERTON (police interview): Can I find out an update on her, please? Is there any way?

The only person who could counter Howerton's story was dead. Investigators hoped Cayley's remains might speak on her behalf. Dr. Suzanna Dana performed the autopsy and said the evidence shows Cayley was beaten to death.

DR. SUZANNA DANA (in court): She had a number of what I call blunt force injuries to her face and her head. …

ALESSANDRA CRANSHAW: And what is this that we see behind the ear?

DR. SUZANNA DANA: That's a bruise. That's a contusion.

But during cross-examination, Hunter gets Dana to admit that at least one Cayley's injuries was caused by her medical care.

JOHN HUNTER (in court): So CPR can cause a lot of different injuries, not just simply superficial ones. Right

DR. SUZANNA DANA: Yes. 

JOHN HUNTER: In this case, a rib was broken. Is that correct.

DR. SUZANNA DANA:  I believe so. Yes.

Whatever the jury thinks about how Cayley died, they're about to learn much more about her troubled love life with Howerton.

A DEFENSE WITNESS MAKES A STUNNING CLAIM

In the agonizing final hours of Cayley Mandadi's life, her friends gathered to say goodbye. Cayley's childhood friend Taylor Clement met her college friends for the first time. They bonded talking about Cayley.

Taylor Clement: Even in that situation, she was bringing people close that would've never met before.

Some of those friends now nervously wait to testify in Howerton's murder trial.

ALESSANDRA CRANSHAW (in court): Do you recognize this person?

MORGAN SAMPSON: I do.

ALESSANDRA CRANSHAW: Who is this individual?

MORGAN SAMPSON (voice breaking): It's Cayley.

According to her roommate, Morgan Sampson, there was a turbulent history between Cayley and Howerton, with a particularly disturbing incident occurring just a few weeks before Cayley's death. Sampson mentioned that Cayley had invited Howerton to a party, which upset him.

In court, Sampson testified, "Mark and Cayley were out on the balcony. And he had thrown her up against the brick wall."

Officer Lewis, who was present at the location, stated, "When I arrived at the location... a male subject was exiting the room."

In a bodycam video, Officer Lewis can be heard asking Howerton, "And so you're in the room just waiting on her while she's at a party?"

Howerton responds, "Exactly."

Officer Lewis then asks, "You mind if I take a look in the room?"

Howerton hesitates, saying, "Man, no..."

Officer Lewis insists, "I would like you to step out here with my partner right now."

Upon entering Cayley's room, Officer Lewis discovers that the glass door to the balcony is cracked and Cayley's clothes are scattered in the trees. Friends later reveal that Howerton smashed Cayley's laptop on the street, leading to his banishment from the university campus.

Cayley had expressed her desire to reconcile with her ex-boyfriend, Jett Birchum.

Christy Jack: "She was really torn between two different people, both of whom were vying for her affection."

Jett Birchum testified in court that the situation reached its climax at the music festival.

JETT BIRCHUM (in court): She told me she wanted to end the relationship with him at Mala Luna because there would be plenty of witnesses and people around.

ALESSANDRA CRANSHAW: Was she concerned about breaking up with him?

JETT BIRCHUM: Yes.

Howerton picked up Cayley to go to the music festival. However, they stopped at a nearby carwash to consume MDMA, or molly. Howerton stated that they took more once they arrived at the festival.

John Hunter: We're talking about large doses, well above the necessary amount for it to have an effect - to induce the desired experience.

When Cayley didn't appear on campus that night, her friends began calling her. Howerton answered Cayley's phone.

MORGAN SAMPSON (in court): I asked him, "Have you seen Cayley?" Or, "Have you heard from her? Are you with her?" And he replied, "She can't talk right now," and then hung up the phone.

In a state of panic, they started searching for Cayley. Jett Birchum, who also attended the festival, claimed to have seen Mark and Cayley moving towards the exit... seemingly against Cayley's will.

JETT BIRCHUM (in court): Cayley appeared as though she was trying to create distance and escape.

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.

Would it surprise you to learn that the phone call you placed to Cayley Mandadi's phone was made at 7 o'clock?

No, sir.

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

You were on probation at the time, were you not, Mr. Birchum?

Correct.

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

… 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.

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?

PARENTS LAUNCH THEIR OWN INVESTIGATION: "CAYLEY GUIDED US"

After just 10 hours of deliberating, the jury in the Mark Howerton murder trial sends a note to the judge. There will be no verdict.

Mistrial Declared in High-Profile Case

JUDGE RAYMOND ANGELINI (reading note): "After careful deliberation and discussion, unfortunately we cannot come to a unanimous decision." Ladies and gentlemen of the jury, I am declaring a mistrial.

Peter Van Sant: Mistrial. Are you happy? Is that in a way, a victory for you?

John Hunter: Any time that your client doesn't go to prison, it's a victory.

Alison Steele (sighs): It was a little bit disheartening. But at the same time, I was mentally prepared for that outcome.

Prosecutors David Lunan and Alessandra Cranshaw were disheartened, too.

Peter Van Sant: Did you feel as though you'd let the family down?

David Lunan: Well, sure.

Alessandra Cranshaw: Yeah.

David Lunan: Absolutely.

But it doesn't end there. The prosecutors plan to retry the case and get busy preparing for round two, starting with the defense star witness, medical examiner Dr. William Anderson.

Alessandra Cranshaw: I was not prepared for Dr. Anderson to testify, uh -- to what he testified to.

They'd been stunned by his claims that Cayley had a skull fracture, and her bruising was caused in part by the organ donation process.

Peter Van Sant: So, do you find that this notion that organ harvesting caused these bruises to be absurd?

David Lunan: Absurd. Absurd. In this instance, it's absurd.

While the prosecutors work to address those claims, defense attorney John Hunter files a motion to get the whole case dismissed, based in part on what he says were Jett Birchum's lies.

John Hunter: The knowing use of false evidence by the prosecution undermines our entire faith and confidence in the judicial system. … If that can happen, then there's no point in even having a trial.

Cayley's mom Alison Steele and stepdad Lawrence Baitland sat through the first trial and concluded jurors needed more information about what happened inside Mark Howerton's car.

Peter Van Sant: You became investigators?

Alison Steele: We did.

Lawrence Baitland: I knew we needed to show what happened in that car. … The jury needed to know how it happened.

She's a scientist, he's a NASA engineer. They got to work.

Lawrence Baitland: I spent hours and hours, um, studying autopsy photos, and I really fixated on one of the autopsy photos that showed an impact on Cayley's head, you know, right in front of her ear. 

The photo of a small dot above Cayley's right ear. Other photos show deep bruising above Cayley's left ear, like the one described by the medical examiner in the first trial.

ALESSANDRA CRANSHAW: And what is this that we see behind the ear?

DR. SUZANNA DANA:  That's a bruise. That's a contusion.

Cayley's parents believe that when taken together, the photos tell a story.

Alison Steele: We believe that of all of the injuries, the blows landed on her … the fatal one occurred when he reached from his driver's seat, hit her in the left ear and drove her head into the window and onto the lock button of the car.

In fact, in a recorded audio interview with police the day Cayley died, Howerton admitted he had previously done just that.

RANGER RAYMOND BENOIST (police interview): Did you ever push Cayley's head up against the window?

MARK HOWERTON: I pushed her, and she hit the window one time. That was over a week ago, yes.

Christy Jack: So, in many respects, it was like, same song, second verse.

They'd need proof to convince a jury. Cayley's parents headed to a used car lot, where Steele posed in a car similar to the Mercedes Howerton drove that night.

Lawrence Baitland: I'd photographed her head in different positions while I'm holding the autopsy images, trying to see if they match up with the door and it's a near perfect match.

Baitland decided to go a step further.

Lawrence Baitland: So, then I loaded this 3D modeling program.

Building a 3D model of Cayley's head.  

Lawrence Baitland: One of the first things you can do is create a solid object from the 3D mesh. Then, you can project an image onto it.

Bringing them closer to obtaining actual evidence.

Lawrence Baitland: This gave me the confidence to take the next step, which was to locate the killer's car.

Mark Howerton sold the car in 2018. Baitland tracked down the new owner and purchased the car.

Peter Van Sant: What did you think of that?

David Lunan: Well, this is new. This is not something I'm used to hearing in other cases.

Peter Van Sant: Show me what you believe happened.

Lawrence Baitland: Sure.

Peter Van Sant: Let's go to the passenger side...

The car that Cayley was fatally injured in is parked in her parents' driveway. Baitland says driving it home was a haunting experience.

Lawrence Baitland: It's torturous. But it's also a way for her to show us what happened. She was guiding us to this car.

Peter Van Sant (standing outside of the car): You believe that he struck her. When he did, she hit her head on this knob. Now you can see that when you push it down, it doesn't go flush.

Lawrence Baitland:  Right. … This will not retract fully, no matter how hard you hit it.

Cayley's parents decided to make a video to demonstrate their theory in court.

Christy Jack: They went and found two actors, a male and a female to dress the parts. They were, um, similar size, similar weight.

Lawrence Baitland: If we did the reconstruction ourselves, it would be considered biased and probably thrown out or at least discredited.

So they hired a private investigator to produce the demonstration. They didn't even look at it in case they were called to testify about it.

The video is simple: showing three angles of what Cayley's parents and their experts believe happened.

Peter Van Sant: Would showing a jury a video like this potentially help the prosecution's case. If it -- if it's allowed?

Christy Jack:  Jurors are very visual. … It makes it easier for them.

Christy Jack: It shows how it can happen. And it answers a number of the questions that the jury had in the first trial.

Hunter says however Cayley got that dot above her ear, it's all speculation.

John Hunter's Speculation

John Hunter, a key figure in the Cayley Mandadi murder case, has made some speculative remarks regarding the cause of her injuries. He suggests that it could have been from something at the hospital or even something that happened before she got into Mark's car. Hunter even goes as far as suggesting that it could have been the work of a space alien. However, he acknowledges that these theories are unscientific and perhaps not worth discussing.

Despite the speculation, Alison worked tirelessly to pass the Texas Clear Alert Bill, which allows law enforcement to swiftly initiate searches for missing individuals between the ages of 18 and 64. In 2021, a district court in Texas rejected John Hunter's motion to dismiss the case, ruling that there was no evidence of prosecutorial misconduct related to Jett Birchum's testimony. Hunter appealed this decision, but his appeals were ultimately unsuccessful, with the United States Supreme Court declining to hear the case.

After more than five years since Cayley's death, a date for a second trial has finally been set for May 23, 2023.

The High Stakes of the Second Trial

Peter Van Sant raises the question of what is at stake in the upcoming trial. Christy Jack, a key figure in the case, responds by saying that the stakes could not be any higher.

JUSTICE FOR CAYLEY

May 2023 marks the beginning of Mark Howerton's second trial for the murder of Cayley Mandadi.

Taylor Clement, a supporter of Cayley, expresses confidence that this trial will bring justice for her.

Recreated News Article

The judge said I'm gonna let it in. But if so … then the parents are now witnesses and they will no longer be allowed to sit in the trial. … And the prosecution went and talked to the parents, and they decided to withdraw the exhibit.

On May 23, trial two begins -- this one without television cameras. Alessandra Cranshaw's opening argument is nearly the same.

Alessandra Cranshaw: I basically told the jury that … the best way to explain this case … is to start where Cayley Mandadi's life ended and that's in the car with this defendant.

But there is a big change to the witness list: no Jett Birchum.

Christy Jack: There was nothing to be gained.

And prosecutors add a witness - an expert on domestic violence who told jurors Howerton was a textbook abuser, who isolated and manipulated Cayley, and ultimately became enraged and lost control.

A pattern particularly difficult to handle at just 19 years of age.

Christy Jack: I think she had no idea, the dangerous predicament she was in.

John Hunter wants jurors to give Howerton the benefit of the doubt.

John Hunter: The … presentation of how Cayley looks in the hospital and how she looked at the autopsy does not mean that she was beaten.

His case, this time around, relies heavily on the testimony of a pharmacologist who said the high levels of MDMA, or ecstasy, in Cayley's system could have caused her brain bleed.

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John Hunter: In my opinion, that was the main cause of her death.

However, prosecutors and Cayley's family argue that Hunter greatly exaggerated the danger of MDMA.

Alison Steele: There has never been a single documented case anywhere of MDMA causing a subdural hematoma.

Peter Van Sant: What is your response to that?

John Hunter: Well, first of all, there hasn't been much research on this topic.

Hunter plans to call one final witness - the former medical examiner whose testimony about organ donation and a possible skull fracture caused significant damage to the prosecution in the first trial - Dr. William Anderson.

This time, prosecutors are prepared for him, as they have a new witness, a respected medical examiner who stated that Anderson's claims in the first trial were irresponsible.

Alessandra Cranshaw: They realized that we were going to be well-prepared to refute all the claims he made in the first trial.

John Hunter: I didn't need to argue about the skull fracture.

So the defense rests without Anderson.

Lawrence Baitland: It was a shock... You could hear a gasp in the courtroom...

Now, a second group of 12 individuals will determine Mark Howerton's fate. It's an agonizing wait for Cayley's parents.

Taylor Clement: Missing My Best Friend

In a recent interview, Taylor Clement expressed her deep longing for her best friend. The loss has been difficult for Clement, who shared a close bond with her companion.

Baitland and Steele, who were involved in a video that was never shown to the jury, have no regrets about the time and money they spent on it. According to Lawrence Baitland, the video helped them learn what happened and they would do it all over again if given the chance.

"48 Hours" provided Steele with her first glimpse of the video. Alison Steele found it hard to watch, as it likely showed the blow that killed her friend.

Despite the tragedy, Cayley's mom continues to fight for justice and to support other victims of violence. She hopes that her daughter's sacrifice can make a difference in the lives of others.

"What I would like is for her sacrifice to help other people. That's what she would want. I have absolutely no doubt about that," says Alison Steele.

Mark Howerton will be eligible for parole in 2033.

Produced by Mary Ann Rotondi and Chris Young Ritzen. Jenna Jackson and Ryan N. Smith are the development producers. Mike McHugh is the producer/editor. Michael Loftus is the associate producer. Gregory F. McLaughlin, George Baluzy and Michelle Harris are editors. Peter Schweitzer is the senior producer. Nancy Kramer is the executive story editor. Judy Tygard is the executive producer.