Cayley Mandadi, 19, was a typical Texas teenager navigating life through school, sports and boys. Her friends say she had a big heart and was “full of love.” Her mother says Cayley was a happy, confident, warm and always smiling person.
Mandadi was a sophomore communications major at Trinity University, a small liberal arts college in San Antonio, Texas. In the fall of 2017, friends say Mandadi finally felt like she fit in at school. She joined a sorority and was a member of the Trinity cheerleading team.
Young love
Mandadi dated Trinity student and football player Jett Birchum during his freshman year. But the relationship was on again, then off.
A new man in Mandadi’s life
There was another man in Mandadi’s life – 22-year-old Mark Howerton. Growing up, Howerton was a star high school baseball player. Howerton was not a student at Trinity, but often visited his friends on campus. This is how he met Mandadi. In October 2017, their friendship turned into a romantic relationship.
A difficult relationship
Howerton and Mandadi’s relationship quickly became difficult. According to campus police, weeks before his death, Howerton destroyed Mandadi’s dormitory. After getting into an argument, Howerton allegedly threw her clothes into trees, smashed a sliding glass door and later smashed her laptop. The Trinity University Police Department was called to the scene and Howerton was banned from campus.
A festive weekend
The last weekend of October 2017, Mandadi and Howerton attended the Mala Luna Music Festival in San Antonio. The couple were taking MDMA, a drug known as Molly or ecstasy. This photo was taken during the music festival.
Tragedy strikes
According to Howerton, on Sunday, October 29, 2017, the couple left Mala Luna shortly after 4 p.m. They argued after seeing Mandadi’s ex-boyfriend Jett Birchum at the festival.
Howerton said they continued to argue in the car, but eventually stopped in a parking lot to have “rough” make-up sex. Howerton would later tell police that sometime after having sex, Mandadi stopped breathing. At one point, he took her to the emergency room.
A disturbing scene
When Howerton arrived at the emergency room, Mandadi was in the passenger seat of his car, almost naked and unconscious. A paramedic said she saw “multiple bruises” on Mandadi’s legs and immediately began CPR.
The hands of Mark Howerton
As medics attempted to save Mandadi’s life, officers on scene questioned Mark Howerton about what happened that night. They took this photo of his hands,
Mark Howerton arrested
Three months after Mandadi’s death, his autopsy report was made public. It showed she died from blunt force trauma to the face and head and called her death a homicide. Several weeks later, Howerton was arrested and charged with murder and sexual assault. He pleaded not guilty and was released on bail.
Defending Mark Howerton
In December 2019, Howerton stood trial in San Antonio for Mandadi’s murder.
“This is a case where there is more than meets the eye and things are not what they seem,” John Hunter, Howerton’s defense attorney, told “48 Hours “.
Mandadi’s ex-boyfriend on the stand
During the trial, Birchum told the jury what he witnessed at the Mala Luna music festival. He testified that he saw Howerton and Mandadi “having an intense conversation” and Mandadi “trying to create space” and “run away.” He said he then saw Howerton “reach out his right arm, hook it around her shoulder and pull her closer. Then turn around and walk away.”
During cross-examination, Hunter asked Birchum about what he said he saw that day. Birchum initially told police he saw Howerton pick up Mandadi and put her in his car as they left the festival. On the stand, Birchum admitted to misleading police about the matter, testifying that he did not actually see Howerton put Mandadi in his car.
The theory of defense
The defense presents a different theory about how Mandadi suffered his injuries that day. They argue that Mandadi’s bruises were the fault of medical staff and not Howerton. They say the cause was linked to the organ donation process and that when medical professionals desperately tried to resuscitate Mandadi seven times, they broke her rib and bruised her body.
Hung jury pushes Mandadi’s parents to launch their own investigation
After 10 hours of deliberations spread over two days, the jury informed the judge that it was unable to reach a decision. A mistrial was declared.
As prosecutors planned to retry Howerton, Cayley’s mother Alison Steele (pictured) and stepfather Lawrence Baitland decided the jury needed more information about what happened inside from Howerton’s car.
Mandadi’s parents develop their own theory
Steele and Baitland focused on an autopsy photo showing a small dot-shaped bruise above Cayley’s right ear and another larger bruise above Cayley’s left ear.
Steele says they believe Cayley’s fatal injury occurred when Howerton “got up from her driver’s seat, punched her in the left ear and slammed her head into the window and into the button.” locking the car.
Steele and Baitland went to a used car lot where Steele posed in a car like the Mercedes Howerton was driving the night Cayley was killed. This is one of several photos Baitland took of Steele posing in the car. He told “48 Hours” that he “photographed her head in different positions while holding the autopsy images, trying to see if they matched the door and it’s an almost perfect match.”
Mandadi’s father-in-law develops a 3D model
Emboldened by the photos he took, Lawrence Baitland, a NASA engineer, built a 3D model of Mandadi’s head. He superimposed photos of Cayley and the autopsy photo showing that spot above Cayley’s right ear.
“That gave me the confidence to take the next step, which was to search for the killer’s car,” Baitland said.
Find the alleged killer’s car and order a reconstruction video
Bailtland found Howerton’s Mercedes. He convinced the owner to sell him the car.
Baitland and Steele then hired a private investigator who produced a re-enactment video of what they believe happened in the car with actors similar in size to Mandadi and Howerton. This is a still image from this video.
Howerton convicted of aggravated assault in second trial
Howerton is seen in court at the start of his second trial in May 2023.
The prosecution decided not to enter Steele and Baitland’s reenactment video into evidence, fearing that cross-examination by the defense on it could harm the case.
The jury did not find Howerton guilty of murder, but rather of aggravated assault causing serious bodily injury. He was sentenced to a maximum of 20 years in prison. He is eligible for parole in May 2033
Mandadi’s parents continue to fight for the victims
Alison Steele turned her heartbreak into action. In September 2019, she successfully passed the CLEAR Alert bill. Now, in the state of Texas, when someone between the ages of 18 and 64 goes missing, an emergency message is sent to the community. Steele wants “Cayley’s story to be used to help other people.”
Friends forever
Taylor Clement will never forget her best friend. She told “48 Hours” that she always planned to have Mandadi as a bridesmaid in her wedding one day and as godmother to her future children. She said this photo of them “smiling at prom is [her] absolute favorite.”
