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For the Love of Cayley Mandadi
For the Love of Cayley Mandadi 42:00

This story originally aired on September 19, 2020. It was updated on June 6, 2023.

Cayley Mandadi, 19, a sophomore at Trinity University, was last seen alive at a San Antonio music festival with her boyfriend Mark Howerton, 22, on Oct. 29, 2017.

Howerton told police that on the night of the concert the couple took party drugs and had consensual sex. At some point, Cayley stopped breathing. He said he rushed her to the nearest hospital, where medical teams tried multiple ways to save her.

"Even the most explicit television shows don't show you what I saw that day," Alison Steele, Cayley's mother, tells "48 Hours" correspondent Peter Van Sant about when she first saw her daughter at the hospital. "Did she fall out of an airplane? Was she thrown off a bridge?"

Mandadi was declared brain dead and taken off life support. Investigators believed the injuries pointed to murder. The medical examiner ruled that she died of blunt force trauma to the face and head. Howerton was arrested on February 28, 2018 and charged with sexual assault, murder and later with kidnapping. Prosecutors thought it was an open-and-shut case, though it would prove anything but. Complicating the investigation was that there were no witnesses.

"This is a case where there's more than meets the eye and things aren't always what they seem," says defense attorney John Hunter.

What caused the injuries? Were some the result of how Cayley was handled by first responders in their dramatic efforts to save her life? Was she beaten? Or did she suffer from a fall at the music festival?


It had been two long days since an unconscious Cayley Mandadi was life-flighted to Kyle, Texas.

Lawrence Baitland: They did CPR on her approximately seven times. … Every time they get her heart started, she would crash, and it would stop again.

Alison Steele: I saw her future and my future disappearing.

Cayley's mother Alison Steele and stepfather Lawrence Baitland were told there was no hope for recovery. Their daughter, once so full of life, was now brain dead.

Peter Van Sant: Based on what you were seeing, what had your daughter been through?

Alison Steele: Some enormous fatal, physical trauma.

Cayley Mandadi
Cayley Mandadi, 19, was a sophomore studying communications at Trinity University in San Antonio, Texas. Taylor Clement

Cayley, just 19 years old, had suffered a traumatic brain injury.

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

Steele and Baitland told doctors Cayley had one last wish: that her organs be donated to help others. Then, Cayley was taken off life support.

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

It was hard to believe that just days before, things seemed to be going well for Cayley. She was a sophomore studying communications at Trinity University, a small liberal arts school in San Antonio.

Cayley's best friend Taylor Clement says she was active on campus. She had joined a sorority and was a cheerleader.

Taylor Clement: She made friends like effortlessly. I was so happy for her because it looked like she was feeling like she was fitting in.

At Trinity, Steele says Cayley was interested in more than just her schoolwork.

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.

Jett Birchum was a Trinity football player and fraternity brother. Cayley had met and dated him her freshman year.

Taylor Clement: She was very proud of him and that relationship.

But Steele says it was typical "young" love and by sophomore year they were on again, off again. 

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

But 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 his friends.  That's where he met Cayley.

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

John Hunter is Howerton's attorney.

John Hunter: And she was finding herself spending a lot more time with Mark. 

Both Birchum and Howerton knew Cayley was seeing the other man, and neither, friends say, liked the competition.  One month into this new relationship with Howerton, Cayley's life would take a fatal turn.

On Sunday, October 29, 2017, at 10:30 p.m., Mark Howerton rushed Cayley to the emergency room in a small rural hospital in Luling, Texas.

While medical staff tended to Cayley, police officers interviewed Howerton in the quietest place they could find, the hospital chapel. It was recorded on the officer's body camera.

Howerton told officers that he and Cayley had spent the weekend at the Mala Luna music festival in San Antonio. There they drank alcohol and took MDMA – a drug known as Molly or ecstasy.

Peter Van Sant: Did Cayley have any drug issues in university life?

Alison Steele: Cayley was known to use recreational marijuana and MDMA and it was a huge point of conflict with us.

Cayley Mandadi and Mark Howerton at the Mala Luna Music Festival in San Antonio. The couple partied heavily, drinking and taking MDMA, a drug known as Molly or ecstasy.  Mark Howerton

Howerton says just hours earlier — between 5 and 6 p.m. — they left the festival in his Mercedes, and soon got into an argument. Cayley told Mark that she still had feelings for her ex, Jett Birchum.

MARK HOWERTON [police interview]:  I was pretty much saying … "You need to get over this dude. He ain't worth your time." I was like, "your friends are fake," I was just telling her all this s—t … I was trying to get it through her head 'cause she can't get it through her head that she doesn't need to be around those people.

Howerton said they then stopped at a Valero gas station parking lot where they had make-up sex.   But their roadside sexual encounter turned rough — very rough. 

MARK HOWERTON [police interview]: We were having sex, I choked her. But it wasn't like I was killing her. It wasn't like that.

Howerton admitted having rough sex was not unusual for the couple.

MARK HOWERTON [police interview]:  I've never hit her. I've slapped her before. She slapped me before. I've never punched her no. I've shoved her.

Police bodycams roll as man describes what happened before girlfriend stops breathing 01:52

But Mark was adamant about one thing throughout the police interview.

OFFICER: I need to know that everything was consensual, for one.

MARK HOWERTON: It WAS. … 500-percent consensual. … It was consensual.

Howerton said after sex, Cayley passed out.

MARK HOWERTON [police interview]:  After we had sex, like she still talked to me for 5, 6, minutes afterwards … That's when she was like, "I'm not feeling good," but then she just passed out. … she was snoring.

He decided to drive Cayley to Houston to spend the night at his place.

MARK HOWERTON [police interview]:  And I was just driving … And she stopped snoring. … I just had a bad feeling in the back of my head when she stopped snoring … So, I looked over at her like "Cayley, Cayley." And I reached over, and I felt her throat. And I didn't feel anything. That's when I started freaking out.

That's when Mark rushed Cayley to the nearest hospital. 

MARK HOWERTON: Do you know if you have a pulse what that means, like, that means you're alive. Right?

OFFICER CALENTINE: Yes. Yeah. If you have a pulse and your heart's beating.

MARK HOWERTON: Why wasn't she responding? [Puts his hands in his lap.]

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 labeled a homicide.  Several weeks after that, Mark Howerton was charged with murder and sexual assault. 

Alison Steele: OK. Here we are. Here's this person. And we need the system to work.  We really need the system to work in this case.

Howerton pleaded not guilty to all the charges and was released on bail. 

John Hunter: There was a music festival. There were a large amount 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.

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


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.

Daniel Conrad: I was ready for this trial to begin for a very long time.

Daniel Conrad was a student at Trinity University, and the editor of the school newspaper, when Cayley died.

Daniel Conrad: Everyone felt some degree of loss mourning the death of a fellow Trinity student.

Now, he is covering Cayley's murder trial for Courthouse News.

JUDGE:  How do you plead, Mr. Howerton?

MARK HOWERTON:  Not guilty, your honor.

In December 2019, Mark Howerton was tried for allegedly kidnapping, assaulting and murdering Cayley Mandadi. Billy Calzada/San Antonio Express-News via ZUMA Wire

Lawrence Baitland: I describe him as a monster to people.

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: I think the best way to tell this story of how this case came about is to start where Cayley Mandadi's life ended. And that's in the car of this defendant.

Prosecutors allege that on October 29, 2017, Howerton forcefully escorted Cayley from the Mala Luna Music festival to his car. He then drove her to a parking lot where prosecutors claim he sexually assaulted and beat her, causing a fatal brain bleed. Photos show Cayley's condition about 18 hours after she arrived at the hospital.

ALESSANDRA CRANSHAW: Cayley is covered with bruises from head to toe … I believe that you will have no reservations about finding this defendant guilty of the offense of murder.

JOHN HUNTER: Things are not always as they seem.

In his opening statement, defense attorney John Hunter attacks the very foundation of the prosecution's case — from the alleged abduction to Cayley's tragic death.

JOHN HUNTER: No one saw anything that transpired between Mark Howerton and Cayley Mandadi that evening on the 29th. There are no eyewitnesses.

And what about all those bruises? Hunter says they most likely came from medical staff, as they tried to revive Cayley at least seven different times.

JOHN HUNTER: She had been worked on within an inch of her life. …  Mr. Howerton did not cause Cayley Mandadi's death.

The state begins its case with paramedic Sharyl Lane, who was driving an ambulance up to the Luling hospital that night when a vehicle suddenly appeared in her rearview mirror.

SHARYL LANE: There's a black car behind us honking and flashing the lights. … Before I even get out, I see a gentleman that's hollering and screaming. I open the door. He's telling me that — his girlfriend is not breathing. And he needs help.

When Lane looked inside Howerton's car, she saw a disturbing scene.

When Mark Howerton arrived at the emergency room, Cayley Mandadi was in the passenger seat of his car, unconscious. Bexar County Court

SHARYL LANE: She was exposed … all the way down. And her pants and her clothes … were in the floorboard by her feet. … She … had bruises on her … I just remember seeing. And that's when I started CPR.

Lane says there were bruises on the inside of Cayley's legs. The defense says medical staff didn't see any on Cayley's face — evidence, John Hunter claims, that Mark Howerton never punched her.

John Hunter: The treating physician at the Luling hospital — approached this as a drug overdose.

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

John Hunter: Correct. But the symptoms she was presenting were consistent with that patient history.

While the medical team fought for Cayley's life, police interviewed and photographed Mark Howerton.

OFFICER CHRIS ADAMS: While I was taking photographs of him, I noticed … the tops of both of his hands.

DAVID LUNAN: Do they look red to you?


DAVID LUNAN: Unusually red?


While doctors tried to save Cayley Mandadi's life, officers on the scene interviewed Mark Howerton about what happened that night. They took photos of his hands. Bexar County Court

Evidence, investigators believe, that Howerton did hit Cayley.

The Mark Howerton arrested back in October of 2017, was an enormously muscled, intimidating figure. Cayley's friends say he used steroids. Two years later, Howerton has shrunk to the point of being unrecognizable to an officer who once questioned him.

DAVID LUNAN: Do you see that Mark Howerton here in the courtroom this afternoon?


A muscular Mark Howerton before his 2017 arrest, left, and two years later at his trial for the murder of Cayley Mandadi. Mark Howerton/CBS News

Mark 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: Can I find out an update on her, please? Is there any way?

DEPUTY:  They're probably not gonna be able to tell us right now, most likely.

But prosecutors were not going to give Howerton a pass just for cooperating. Why? They believe he lied to investigators about where he had sex with Cayley. In his last interview with law enforcement, the same day that Cayley was removed from life support, Howerton changed his story.

MARK HOWERTON: We didn't have sex at the gas station, we had sex somewhere before the gas station. After that we went to the gas station. 

RANGER RAYMOND BENOIST: Where'd you have sex at? 

MARK HOWERTON: It was just a parking lot. It was empty. … After we had sex at that parking lot is when she told me she wasn't feeling good and she passed out.

The new sex location was the parking lot of a hamburger chain's office building — more than a 40-mile drive from the gas station.

ALESSANDRA CRANSHAW:  If you're gonna conceal something, right, if you're gonna lie about something, it's probably because that's where the crime occurred.

Cayley Mandadi, 19, was a typical Texas teenager navigating life through school, sports and boys. Friends say Cayley had a good heart and was "full of love." Her mother says Cayley was a happy person who was trusting, warm and always smiling. Trinity University

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 prosecutors now hope her testimony will convince jurors that Howerton beat Cayley to death.

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

ALESSANDRA CRANSHAW [pointing to a photo of Cayley]: And what is this that we see behind the ear?

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

Daniel Conrad: So, we got to see a lot of — photographs from the autopsy. … I saw those images … it looked like a girl who was badly beaten, that's kind of how anybody looking at it would say.

But during the cross-examination, John Hunter challenges Dr. Dana's conclusions, suggesting it was the medical staff — and not Mark Howerton — who created much of that bruising.

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


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

DR. SUZANNA DANA:  I believe so. Yes.

Peter Van Sant: The medical examiner says the cause of death is complications of blunt force face and head trauma and the manner of death is homicide. … Is the examiner wrong?

John Hunter: I believe the examiner is definitely wrong.

Peter Van Sant: If you can undermine Dr. Dana, you can at least create reasonable doubt.

John Hunter: No doubt. It's one of the most important features of the case.

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


Peter Van Sant:  When somebody asks you … what was Cayley like, how do you answer that?

Taylor Clement:  Bubbly, happy ... She was just — was an awesome friend. I mean … you want her to be your best friend.

Some of those friends now nervously wait to testify in the trial of the man charged with Cayley's murder, Mark Howerton.  Prosecutors hope they can provide eyewitness details of Howerton's stormy history with Cayley.

ALESSANDRA CRANSHAW: I'm showing you what's been marked State's Exhibit Number One. Do you recognize this person?


ALESSANDRA CRANSHAW: Who is this individual?

MORGAN SAMPSON [voice breaking]: It's Cayley.

Her roommate, Morgan Sampson, recounts one particularly disturbing incident just a few weeks before Cayley's death. She was planning to go to a party.

In court, Morgan Sampson, Cayley's roommate, recounted a disturbing incident that happened just a few weeks before Cayley's death. CBS News

MORGAN SAMPSON: And I invited Cayley to come with me. And at that point — I asked her out loud, and Mark got really upset about it.

ALESSANDRA CRANSHAW: And when you went back into the room what happened?

MORGAN SAMPSON:  At that point, Mark and Cayley were out on the balcony. And he had thrown her up against the brick wall –

ALESSANDRA CRANSHAW:  Did they appear to be having a happy conversation?


Cayley ended up going to that party against Howerton's wishes. He was not happy. Cayley's neighbor, Caro Cortez, describes what she heard next door while Cayley was away.

CARO CORTEZ: There was some banging and we could hear a male's voice saying — "I'm gonna smash your face in." …  saying violent things and doing violent things. … No one responded, so I assumed no one was in there with him.

DAVID LUNAN: And that was alarming to you?


Campus police officer Roderick Lewis was dispatched to investigate.

OFFICER RODERICK LEWIS:  When I arrived at the location, I made my way to the fifth floor and as I was going down the hallway to — room 561 … a male subject was exiting the room.

A bodycam image of Mark Howerton outside of Cayley Mandadi's Trinity University apartment after a neighbor called campus police. "It was completely destroyed," Cayley's roommate, Morgan Sampson, said of their apartment. Bexar County Court

OFFICER LEWIS: So, this is not your room?

MARK HOWERTON: No, this is my girl's —

OFFICER LEWIS: Is she here?

MARK HOWERTON: No, she's at a party.

OFFICER LEWIS:  And so, you're in the room just waiting on her while she's at a party?



MARK HOWERTON: I can call her right now if you want proof.

OFFICER LEWIS: You mind if I take a look in the room?

MARK HOWERTON:  Man, no. This isn't even my house.

OFFICER LEWIS: I understand that —

MARK HOWERTON: There's nothin' in here. But for real. Come on —

OFFICER LEWIS: Well, I wanna see if —


OFFICER LEWIS:  — anything's missin' here.

MARK HOWERTON: No, there's nothin' missing here —

OFFICER LEWIS: Again, it's not your room, so you don't have the option here. …  I would like you to step out here with my partner right now.

Once Howerton stepped out of the room, Officer Lewis went in. It had been torn apart.

Morgan Sampson: It was completely destroyed.

The glass door to the balcony had been cracked, and Cayley's clothes were scattered in the trees. Friends say Howerton later smashed Cayley's laptop on the street. The university barred him from campus.

Lawrence Baitland | Stepfather: Cayley was done with him — completely done. She didn't take his texts, didn't take his phone calls, nothing.

Howerton was reportedly enraged, and he wasn't about to go away.

Lawrence Baitland: So, he escalated, and he allegedly Snapchatted a picture to her with him suckin' on a pistol, sayin', you know, "I'm gonna commit suicide if you don't return my calls."

Cayley's friend Ariana Conway.

Ariana Conway: He was saying that he was gonna kill himself if she broke up with him. And she didn't want to have something like that on her conscience.

Lawrence Baitland: We all know as adults that that's just manipulation. He's a grade A predator. He didn't try … to commit suicide. He was trying to manipulate her into doing what he wanted.

But Cayley was now caught up in a dangerous emotional triangle. She told her ex-boyfriend, Jett Birchum, that she wanted to get back with him.

Cayley Mandadi and her ex-boyfriend Jett Birchum. Alison Steele

John Hunter: Cayley's not sure what she wants. That's pretty evident.

She texted Birchum: "I'm literally in love with both of you…"

This all came to a head on the last weekend of October 2017. Cayley told Birchum she would break up with Mark Howerton at the Mala Luna Music Festival.

JETT BIRCHUM: She had told me that she was planning to break up with Mark on Sunday. And after spending the previous night with him, it confirmed that, like, she wanted to be back with me. And she said she wanted to break up with him at Mala Luna 'cause there'd be plenty of witnesses and people around

ALESSANDRA CRANSHAW: Did she seem worried about breaking up with him?


When Howerton went to pick Cayley up at her dorm room for the second day of the festival, she wasn't there. Howerton's friend, Joe Goodwin, was with him.

ALESSANDRA CRANSHAW: How did the defendant's attitude change while waiting for Cayley?

JOSEPH GOODWIN: He was — getting steadily angrier 'cause he did not wanna wait on her. So, then we got in the vehicle. And he asked her, "Where were you?" … She had no response. He then said somethin' along the lines of, like, "That's bull——. And then we proceeded to drive towards the festival.

But first they pulled into a nearby car wash to take drugs.

JOE GOODWIN: He breaks out a bag of — Molly. And he gives — Cayley some, he gives me some. And — then we continue on towards the festival.

When they got there, they put more Molly in a water bottle and started drinking from that.

John Hunter: We're talking about massive doses, well above what would be necessary for it to affect — be effective— to gain the experience. Combined with consuming large amounts of alcohol.

Soon after they arrived, Howerton told Goodwin he and Cayley were going to get drinks. Jett Birchum, who was also at the festival, says he saw them leave … seemingly against Cayley's wishes.

JETT BIRCHUM: Cayley looked like she was tryin' to create space and kinda just get away. And it looked like they were havin' an intense conversation.

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.

During trial, Cayley's ex-boyfriend, Jett Birchum, told the jury what he witnessed at the Mala Luna Music Festival. He testified that he saw Howerton and Cayley "having an intense conversation" and Cayley "trying to create space" and "get away." He said he then witnessed Howerton, "reach out his right arm and hook it around her shoulder and pull her in closer. And then turn and walk away." Billy Calzada/San Antonio Express-News via ZUMA Wire

When she didn't show up at the dorm or a sorority meeting that evening, Cayley's friends started calling her — worried that she was in danger.

ALESSANDRA CRANSHAW: Now who answered when you FaceTimed Cayley?

MORGAN SAMPSON: The defendant. … I first asked, I was like, "Have you seen Cayley?" Or, "Have you heard from her?" Like, "are you with her?" And he said, "She can't talk right now," and then hung up the phone.

Panicked, they kept trying to contact Cayley. Then, friend Dominique Hussain received an ominous Snapchat.

DOMINIQUE HUSSAIN: I got a video recording of Mark Howerton saying, "Go f—- yourself, you stupid bitches."

ARIANA CONWAY: And then that's when we all started more actively looking for her off campus.

Birchum searched for Cayley as urgently as anyone that night. But, at trial, his version of events would soon be dramatically challenged, surprising everyone.

Peter Van Sant: What was it like to watch Jett Birchum's story come apart?

Allison Steele: [Sighs]


On day four of Mark Howerton's murder trial, he repeatedly comes face-to-face with his former romantic rival for Cayley Mandadi: Jett Birchum, a key prosecution witness.

ALESSANDRA CRANSHAW: Do you see Mark Howerton here in the courtroom today?

JETT BIRCHUM:  Yes, ma'am. …The blue suit.

Birchum's eyewitness account of Howerton's behavior towards Cayley as they left the festival, led investigators to charge Howerton with kidnapping her and causing Cayley's death.

Mark Howerton
Mark Howerton was arrested on February 28, 2018, and charged with sexual assault, murder and later with kidnapping. Bexar County Court

JETT BIRCHUM: And it looked like she was nervous and tryin' to separate herself as in, like, create distance between the two of them. Then I saw Mark reach and grab her with his right arm.

Peter Van Sant: Mark Howerton pulls Cayley Mandadi into his car. … Sexually assaults her.  Beats her to death in a rage-filled murder.  Is that how you see it?

John Hunter: No. Not all all. … It's not a homicide. … This is … a terrible, terrible accident.

To back up his claim, defense attorney John Hunter attacks Birchum's credibility, asserting that Birchum lied to investigators about what he really saw that day.

JOHN HUNTER:  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 that differs from the testimony that you gave to the grand jury, doesn't it?

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.

Peter Van Sant: He lied?

John Hunter:  Jett lied to the grand jury.

Lawrence Baitland: He concocted part of that story to try to get the police to respond out of desperation that they felt for her situation.

Alison Steele: Right. His exact words were, "I exaggerated."

Lawrence Baitland: And then once he was trapped into that storyline, he repeated it for the grand jury as well.

John Hunter hands Jett Birchum copies of photos found on his phone.

During cross-examination, defense attorney John Hunter grilled Jett Birchum about what he says he saw that day. Birchum originally told police that he saw Mark Howerton pick Cayley Mandadi up and put her in his car as they were leaving the festival. On the stand, Birchum admits to lying about this to the grand jury, saying he didn't actually see Mark put Cayley in his car. Billy Calzada/San Antonio Express-News via ZUMA Wire

JOHN HUNTER:  Mr. Birchum … I'd like you to take a look at these … This consists of several large bags of marijuana, does it not?


JOHN HUNTER: This was on your phone, wasn't it?

Next to John Hunter in court is Birchum's attorney. He's here because the photos may implicate Birchum in serious crimes. It turns out he was on probation for a drug charge at the time of Cayley's death.

JOHN HUNTER: You were distributing large quantities of marijuana to the students at Trinity University and people throughout San Antonio, were you not?

JETT BIRCHUM: I wish to assert my rights as provided by the Fifth Amendment.

JOHN HUNTER: In the course of your workings as a drug dealer, part of the profession requires that you document the materials that you are trying to sell to people, correct?

JETT BIRCHUM: I wish to assert my rights as provided by the Fifth Amendment.

During 47 minutes of brutal cross examination, Birchum "takes the fifth" 30 times when asked about his drug activity while on probation.

BIRCHUM'S ATTORNEY [whispers to Birchum]: Same answer.

JETT BIRCHUM: I wish to assert my rights as provided by the Fifth Amendment.

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

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

And it's not clear why Birchum needed to take the fifth at all. He already had a deal with prosecutors.

JOHN HUNTER:  You were offered immunity in exchange for your testimony, correct?


John Hunter: He had got the golden ticket. … And all he's gotta do in exchange for that is testify.

Peter Van Sant: It questions his credibility.

John Hunter: Exactly, it calls into question his credibility completely.

And Hunter is unrelenting on Birchum's troubled past, including an allegation that he committed sexual assault.

JOHN HUNTER:  Were you aware that there was a Title IX  investigation against you?

JETT BIRCHUM: I was aware, yes.

JOHN HUNTER:  And that it pertained to an alleged sexual assault?


Birchum transferred to another university, and says he was told the assault investigation was not ongoing.

When the defense presents its case, they bring Dr. William Anderson to the stand.

DR. WILLIAM ANDERSON: I reviewed the medical examiner's autopsy, medical records … and the photos which were included with the autopsy.

Dr. William Anderson is a forensic pathologist and a former medical examiner who has conducted more than 8,000 autopsies. He challenges the prosecution's claims that Cayley was beaten.

DR. WILLIAM ANDERSON: Three separate observers did not see any injuries to the facial area when she arrives at the emergency room.

Three months after Cayley Mandadi's death, her autopsy report was released. It showed that Cayley died from blunt force face and head trauma, and labeled as a homicide. Bexar County Court

DR. WILLIAM ANDERSON: We don't see any fractures to the eye sockets. We don't see any fractures to the nose. We don't see any kind of fractures on the face. That's a pretty good indication … we're not talking about a full-frontal assault.

In fact, Dr. Anderson tells the jury that Cayley's autopsy photos indicate her brain bleed may have been caused not by a beating, but perhaps by a fall at some point when she was not in Mark's car.

DR. WILLIAM ANDERSON [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.

JOHN HUNTER: What we should take away from this is that this injury's consistent with a fall?


Lawrence Baitland and Alison Steele believe their daughter was beaten to death. CBS News

Lawrence Baitland:  She never left the vehicle for 5 or 6 hours, you know? It just –

Alison Steele: Near as anyone can tell, yeah.

Lawrence Baitland: – it doesn't make any sense.

And as for the bruises all over Cayley's body, Dr. Anderson says they may have been caused by internal bleeding, brought on by long stretches without a heartbeat, and preparation for organ donation.

DR. WILLIAM ANDERSON: So, you look at the autopsy you're going to see … what looked like bruises.

Peter Van Sant: The pictures could be … picking up detail that had to do with the organ donation, and not a potential assault?

John Hunter: Precisely.

The defense also puts on the stand pharmacologist Jason Wallach, an expert in Molly —MDMA — the drug Cayley and Howerton were using.

JASON WALLACH: You know, the — the level of MDMA — in her blood was 980 nanograms per mil. And that's — that's high.

According to Dr. Wallach, high blood pressure from MDMA increases the chance of a hemorrhage.

JOHN HUNTER: In a situation such as this, it's possible that someone sustained a minor head injury and by result of the MDMA it became a fatal condition?


Once the defense rests, prosecutors bring Dr. Dana back to the stand in hopes she can shut down these alternative theories of Cayley's death — particularly the notion that a fall killed her.

ALESSANDRA CRANSHAW: Did you have an opportunity when conducting the autopsy to closely examine the skull?


ALESSANDRA CRANSHAW: Is that a skull fracture?

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

The jurors now hear closing arguments. The state refocuses on Cayley and the man they say murdered her.

ALESSANDRA CRANSHAW: She was just starting out her life. She was just beginning her life. And she got into the car with that defendant. … This is what happened to Cayley Mandadi. … It wasn't medical staff. It wasn't the post-mortem organ donation that did this to her. It was the defendant.

The defense says that while Mark Howerton is no angel, he also isn't a killer.

JOHN HUNTER: There is no evidence that Mr. Howerton caused this death at all. … Their side of the story doesn't make sense; it doesn't add up. … Mark Howerton is not guilty.

John Hunter: We're talking about a charge that if he's convicted of it, it's life in prison.

Peter Van Sant: Has your belief that your daughter was beaten in any way been changed by what was presented at trial?

Allison Steele:  Not in the slightest.  Not at all, no. … She was beaten to death.

And then, just a few hours into jury deliberations, the defense receives a shocking phone call that could impact the outcome of the trial.

JOHN HUNTER [at bench]: We had no idea this person existed.


Just hours after the jury begins deliberations, John Hunter unexpectedly learns of a new witness who claims to have seen crucial evidence that was not introduced at trial.

John Hunter: We were walking back to the office and I see that we have missed calls …

John Hunter: I got a phone call … from a person who advised me that they were working the front desk of the hospital on the night that Cayley was brought in … she saw her pale, white legs there were no bruises on her legs … she thinks that the EMT's testimony is wrong.

Cayley Mandadi Alison Steele

Remember, this is what the paramedic who treated Cayley said she saw that night:

SHARYL LANE: She … had bruises on her, multiple bruises … that I just remember seeing.

JOHN HUNTER: You observed bruising on the inside of her legs, correct? Yes.

But Hunter says this new witness would turn that description on its head, supporting the defense claim that Cayley's bruises came after she was admitted to the hospital, and were not caused by Mark Howerton. 

John Hunter: That's a very significant point in my mind.

But the judge says it's too late to call the new witness.

John Hunter: We've got this information. It's frustrating that the jury doesn't know about it. But it's encouraging because if things don't work out, this is the kind of thing that might get the courts to pay attention.

Now all he can do is wait for the jury to come back with a verdict.

John Hunter [in his office]: We have no clue what they're thinking.

Lawrence Baitland: We didn't know what to expect.

Lawrence Baitland and Alison Steele say they couldn't wait for it to be over.

Lawrence Baitland: We didn't know if it would be quick. We didn't know if it'd take days.

After just 10 hours of deliberating over two days, the jury sends a final note to the judge. There will be no verdict.

JUDGE RAYMOND ANGELINI: After careful deliberation and discussion, unfortunately we cannot come to a unanimous decision. All jurors have expressed their strong position and inability to change their position with the evidence provided. … 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, no matter what the facts are, no whatever what the circumstances.

Alison Steele: [Sighs] It was a little bit disheartening. But at the same time, I was mentally prepared for that outcome.

Both sides say they are not backing down. The prosecution plans to retry the case – a decision John Hunter strongly disagrees with, since, he says, their star witness Jett Birchum lied to the grand jury.

John Hunter: Why should they get another bite at the apple?

Alison Steele: Hey, we're not done yet. We're gonna pick this back up again …

Alison Steele and Lawrence Baitland are determined to get justice for their daughter.

Alison Steele: There is no doubt in our minds what happened.

Alison Steele: I believe it was murder, straight up, every day, twice on Sundays.

Since her death, Steele visits Cayley's room every day.

Alison Steele: This is Cayley's room — it is as she left it. … We have a lot of mementos here …

Peter Van Sant [pointing to words above Cayley's desk]: I love this saying, "You will forever be my always."

Alison Steele: No truer words spoken than that because she will always be more to me than I ever thought a human being could.

At Cayley's desk, Alison Steele has tirelessly worked to turn her grief into action. In September 2019, less than two years after Cayley's death, the Texas Legislature approved the Coordinated Law Enforcement Adult Response, or CLEAR Alert. CBS News

At her daughter's desk, Steele has tirelessly worked to turn her grief into action. In September 2019, Alison was able to get the CLEAR Alert bill passed.

ALISON STEELE [in front of audience giving speech]: CLEAR Alert, as you are going to see, is a game changer. … There was an Amber alert for children, there was a silver alert for seniors … so anybody else whose life was in danger for any reason, they were kind of out of luck."

Now in the state of Texas, when someone between the ages of 18 to 64 goes missing, an emergency text will go out to the community.

Alison Steele: We cannot change what happened. But I want Cayley's story to be used to help other people.

Taylor Clement: The one of us like smiling at prom is my absolute favorite picture.

Cayley Mandadi, left, with best friend Taylor Clement.  Taylor Clement

Taylor Clement treasures the time she had with her best friend. 

Taylor Clement: She was gonna be my maid of honor and godmother to my children and there was no doubt about that. … There are things that I hold that I don't tell anybody. And I know I could tell her. I miss that.

Editor's note: In June 2023, Mark Howerton was retried and found guilty of aggravated assault, not murder. He was sentenced to 20 years in prison.

Produced by Chris Young Ritzen and Ted Gesing. Claire St. Amant and Ryan Smith are the development producers. Doreen Schechter and Greg Kaplan are the editors. Peter Schweitzer is the senior producer. Nancy Kramer is the executive story editor. Judy Tygard is the executive producer.  

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