Cellphone data showed where Trinity University student was following music festival

Day 5 of Mark Howerton retrial

SAN ANTONIO – Critical cellphone data shown to a jury Tuesday plotted out the locations where a Trinity University student and her boyfriend were before she showed up unconscious at a hospital.

Mark Howerton is on trial for the murder of his girlfriend, Cayley Mandadi.

On Oct. 29, 2017, Howerton showed up to a Luling hospital with a seminude, unconscious Mandadi, who wasn’t breathing and covered in bruises.

Guadalupe Sheriff Office Lt. Zachary McBride was asked by Texas Rangers to help analyze the cellphone GPS data from Howerton and Mandadi’s phone.

Here’s is a timeline of what McBride was able to plot for that day:

  • 2:37 pm - Howerton’s phone was at Trinity University
  • 3:42 pm - Howerton’s phone was near the area of Wolff Stadium where the Mala Luna Festival was taking place
  • 4:05 pm - Howerton’s phone was in the area off Highway 281 by the corporate Whataburger offices across from the Quarry
  • 4:23 pm - Mandadi’s phone starts showing up in the same area off Highway 281
  • 5:33 pm - Mandadi’s phone is still showing up at the corporate Whataburger offices
  • 7:14 pm - Mandadi’s phone is now in the area off Loop 410 near San Antonio International Airport
  • 7:27 pm - Howerton’s phone is now in the same area near the airport
  • 10:39 pm - Howerton’s phone is now in the area of Interstate 10 near Luling

These locations would dispute Howerton’s first version of what happened after leaving the music festival. He had told police the two stopped at a Valero off I-10 to have make-up sex before proceeding to Houston.

The cellphone data would also show that Howerton drove around for awhile before showing up at the Luling hospital.

In other testimony Tuesday, Mandadi’s best friend, Ariana Conway, also took the witness stand.

Conway said the week before Mandadi’s death, she had gone with Mandadi to try to get her phone from Howerton, which upset and agitated him.

Howerton took a gun out of his car and started threatening her, Mandadi and some of their other friends, Conway testified.

Conway said they were able to deescalate the situation by just agreeing with whatever Howerton was saying to them.

After the incident, Conway said that Howerton kept calling Mandadi and threatening to kill himself if she broke up with him.

On Oct. 29, 2017, Conway said she was concerned when Mandadi had missed a mandatory sorority meeting. When Conway tried to contact Mandadi, she got a text back that she didn’t think was written by Mandadi.

Conway also testified that she got a quick SnapChat video from Mandadi that briefly showed Howerton in the clip saying “Shut up you stupid bitch.”

Conway said after the video she never received any more texts or videos from Mandadi’s phone.

The state could rest as early as Wednesday with only a few more witnesses left.

This is the second time Howerton is on trial for the murder charge. In 2019, the trial ended after the jury couldn’t reach a decision.

If found guilty, Howerton is facing up to life in prison.


About the Authors:

Erica Hernandez is an Emmy award-winning journalist with15 years of experience in the broadcast news business. Erica has covered a wide array of stories all over Central and South Texas. She's currently the court reporter and cohost of the podcast Texas Crime Stories.

Misael started at KSAT-TV as a photojournalist in 1987.