SAN ANTONIO – Attorneys for a man accused of a Trinity University student’s death have moved to bar his retrial, citing prosecutor misconduct and double jeopardy after his 2019 trial ended in a hung jury.
Bexar County District Attorney Joe Gonzales previously said that he would retry Mark Howerton in 19-year-old Cayley Mandadi’s death. Defense attorneys announced this week that they filed a writ of habeas corpus “seeking relief from double jeopardy.”
“The law affords the prosecution ‘one full and fair opportunity to convict,’” defense attorney John Hunter said in a news release.
Howerton faced murder, rape and kidnapping charges in the initial trial in December 2019. Jurors spent nine hours deliberating over two days if Howerton, Mandadi’s boyfriend at the time of her death, was guilty.
Though the panel declined to discuss the case with the media after the mistrial was declared, the foreman told KSAT that the vote was 8-4 in favor of a guilty verdict. Howerton faced a maximum punishment of life in prison.
The indictment against Howerton remained in place as Gonzales said “we have every intention of going forward” at the time.
Following the announcement from Howerton’s attorney’s this week, the district attorney’s office said they will not comment pending litigation. The case was scheduled to be retried this month, but it will be delayed due to the writ.
A hearing will take place where the judge will decide on the motion. That hearing isn’t scheduled yet.
Defense attorneys also argued misconduct by the prosecution in the writ of habeas corpus.
They said the state called Mandadi’s ex-boyfriend as a witness, and he testified that he saw Howerton pull Mandadi into to crowd at the Mala Luna Music Festival on Oct. 29, 2017, after an argument.
Data from cell phone towers and GPS showed that Mandadi and Howerton were not at the festival at the time of the alleged incident, defense attorneys said.
“This isn’t a case where we [the Defense] had to go and independently dig up proof that the witness had lied,” Hunter said. “The cell phone data provided by the prosecutors contained all of the cell tower and GPS data necessary to show that Cayley’s ex-boyfriend could not have seen what he testified to seeing.”
“The State’s decision to call this witness at trial and sponsor his false statements in spite of that evidence shocks the conscience. But they decided to sponsor his testimony anyway because he was the only person who claimed to have observed anything remotely violent between Mark and Cayley the weekend leading up to her death.”
Back in 2017, Howerton told investigators that the couple stopped to have consensual sex while driving to Houston, and Mandadi stopped breathing. Medical experts testified that the teen died as the result of blunt force trauma to the head.
According to testimony during the trial, the couple had been dating but Mandadi was planning to end the relationship. Witnesses testified that Howerton was controlling and possessive.
Mandadi was a sophomore at the private San Antonio university and on the cheerleading squad at the time of her death.
Mandadi’s mother filed a wrongful death lawsuit against Howerton and Trinity University in June.
The civil lawsuit, filed by Alison Steele on behalf of Mandadi’s estate, alleges that Howerton sexually and physically assaulted her “multiple times” over the course of their relationship, and caused her death by drugging and assaulting her.
The civil lawsuit also alleges that that Mandadi’s death was preventable, claiming that Trinity University failed to respond to multiple reports of stalking, abuse, intimidation and domestic violence and accuses the school of gender-based discrimination. The suit seeks at least $1 million in damages.