Trial of Mark Howerton for murder of Cayley Mandadi ended in mistrial: 48 Hours on ID investigates

Mugshot of Mark Howerton
Mark Howerton was accused of murdering girlfriend Cayley Mandadi, but a jury failed to reach agreement. Pic credit: Bexar County Sheriff’s Office

48 Hours on ID is examing the case of Cayley Mandadi, a cheerleader from Houston, Texas, who died after attending a music festival with her boyfriend, Mark Howerton.

In October 2017, Mandadi and Howerton attended a music festival in San Antonio, which was the last place the 19-year-old cheerleader was seen alive.

Howerton claims that the couple had spent the night taking drugs and having consensual sex, but at some point in the night, Mandadi stopped breathing, so he took her to a nearby hospital.

When they arrived, Mandadi was barely breathing and was covered in multiple injuries from head to toe. She was also naked from the waist down, and her blouse had been pulled up to her shoulders. She was declared brain dead and died of her injuries a few days later, on October 31.

Mandadi’s mother would later state that her injuries were so bad it looked like she’d fallen out of an airplane.

The medical staff subsequently concluded she had been sexually assaulted and had died from blunt force trauma to the face and head.

Mark Howerton was viewed as controlling and possessive of Cayley Mandadi

The police focused their investigation on Howerton, who they learned was controlling and possessive of his girlfriend. The pair had a stormy relationship, and Howerton had trashed her dorm room during an argument a few months before her death.

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The investigators concluded that the pair had argued as they drove home from the concert and that Howerton had snapped and killed Mandadi when she told him she wanted to end the relationship.

Howerton told them they had argued on the night she died and that they had engaged in consensual rough make-up sex. He claimed it was during sex that she suddenly stopped breathing.

Howerton was arrested and charged with murder, sexual assault, and kidnapping. However, the subsequent trial in December 2019 ended in a mistrial when the jury failed to reach an agreement.

The defense lawyers had argued that their client was innocent and that the majority of the injuries to Mandadi were caused by medical staff at the hospital as they tried to revive the cheerleader.

A retrial has been scheduled to take place in 2021.

More from 48 Hours on ID

Follow the links to read about more heinous crimes profiled on 48 Hours on ID.

Christopher Brandon Lee was having an affair with a fellow marine’s wife, Erin Corwin. He killed her when she became pregnant and dumped her remains down an abandoned mineshaft in the Californian desert.

Ensign Andrew Lee Muns murdered by Michael LeBrun on the USS Cacapon in 1968. Tragically, in his absence, Muns was accused of stealing the ship’s payroll and deserting. It took 30 years for the truth to finally emerge.

48 Hours on ID airs at 10/9c on Investigation Discovery.

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