DeLuna was charged with killing a gas station attendant, 24-year-old Wanda Lopez, on the evening of February 4, 1983, in Corpus Christi, Texas. The young woman died from multiple stab wounds, apparently from a buck knife. Lopez was killed while on the phone with the police, having just called 911 to report a suspicious person who turned out to be her killer. The crime was particularly senseless because, according to the 911 tape, Lopez seemed to be giving her attacker the money at the time she was stabbed, saying “You want it? I’ll give it to you. I’ll give it to you. I’m not going to do nothing to you. Please!!!”

Police arrived shortly after Lopez’s 911 phone call ended and spread out across the area searching for the suspect. The police radio traffic describing the manhunt reveals a chaotic search, with police pursuing several leads towards differing locations with varying suspect descriptions. After first chasing a suspect – repeatedly identified in police radio calls as a male suspect – fleeing on foot several blocks away and further north of the store, police received a 911 call from a neighborhood resident Esther Barrera, who saw someone hiding under a truck in front of her home. Police briefly detained a female several blocks from where they last reported to be chasing the first suspect.[26] Police also briefly stopped a car described as “a blue Mercury or LTD” and occupied by “two Hispanic males” in the area of the first suspect chase.

Police eventually found DeLuna, 30–40 minutes after the crime, hiding a few blocks away from the Shamrock gas station underneath a parked truck. Despite it being a cold February night, he had on no shoes or shirt and was lying in a puddle of water. The police pulled him out, and found that he had a black wallet containing 2 one dollar bills in his rear pocket, and a “wad” or “clump” of bills totaling $149 in the front pocket of his dark pants.  Despite the extremely bloody crime scene, no blood was ever found on Carlos DeLuna. Allan Bayle, a forensic expert assisting the Columbia team, opined that Lopez was behind the counter handing her attacker the money, while the attacker remained in front of the counter.  This opinion conflicts with the report of two eyewitnesses to the attack (Baker and Aguirre) who both said they saw the attacker wrestling with Lopez. Baker told police he saw the attacker attempting to drag Lopez by the hair into a room at the back of the store.

Two attorneys were appointed to represent DeLuna at trial. The first, Hector De Pena, Jr., was the son of a local judge and a former Deputy District Attorney and County prosecutor who had been in practice since 1972. After the trial, De Pena was elected to the bench, where he has remained. Since De Pena had never represented a criminal defendant in front of a jury on any kind of serious criminal charge, the judge also appointed a seasoned criminal defense attorney, Jimmy Lawrence, to serve as the “first chair” trial attorney. As the more experienced attorney, Lawrence conducted most of the direct and cross-examinations, and gave the closing argument in both the guilt and penalty phases. In their 2012 report on the case, Columbia University researchers noted that many in the Corpus Christi legal community at the time suspected De Pena was appointed to the case as a favor from the case judge (Jack Blackmon) to De Pena’s father, Hector, Sr., a long-time local judge.

DeLuna took the stand in his own defense and testified as follows: He spent the early evening with two sisters, Mary Ann Perales and Linda Perales. A man named Carlos Hernandez approached them. Although DeLuna did not originally recognize Hernandez, after talking to him he realized that they had known each other as kids. DeLuna testified that he was wearing a blue shirt, black pants, and black slip-on shoes. Thereafter, DeLuna and Hernandez went to a bar named Wolfy’s, located directly across the street from the Shamrock gas station. Hernandez said he was going over to the Shamrock to buy something, so DeLuna ordered a beer at Wolfy’s and waited. DeLuna began wondering why Hernandez was taking so long, so he stepped outside Wolfy’s to see what was going on. DeLuna could see across the street and into the Shamrock and observed Hernandez attacking Lopez. Worried that people might say he was involved with Hernandez, DeLuna started walking away on Dodd toward Nemec (i.e., not in the direction of the Phase III where the Arsuagas saw a man running). When DeLuna heard sirens, he started running. He testified that his shirt was ripped clean from his body while climbing over a fence.  The rolled up bundle of bills in his pocket was from two recent paychecks.

On cross-examination, DeLuna was asked about the white shirt and shoes that were found in a nearby yard, and he testified that they were not his. DeLuna admitted that he was a twice convicted felon and that he had lied to the psychiatrists who examined him. DeLuna admitted he was unable to identify Carlos Hernandez from his mugshot.  The prosecution offered rebuttal evidence to show that one of the sisters that DeLuna claimed to have been with that evening, Mary Anne Perales, was actually attending her baby shower, DeLuna lied about his whereabouts that afternoon to his parole officer,[56] and  DeLuna frequented the Casino Club. Carlos Hernandez was also known to be a regular at the Casino Club.

After deliberating for four and a half hours, the jury convicted DeLuna of capital murder. At the penalty phase, the prosecution introduced evidence that DeLuna had committed two attempted rapes. The prosecution called Juanita Garcia, the 54 year old invalid mother of DeLuna’s best friend. Sentencing 22-25. DeLuna attempted to rape her just 2 days after his release from prison on an earlier conviction for attempted rape, breaking three of Garcia’s ribs. This incident caught DeLuna’s lawyers by surprise, since he had only been charged with misdemeanor assault in this incident so they did not thoroughly investigate it. The jury deliberated for six hours before deciding that DeLuna was likely to reoffend, whereupon the judge sentenced him to death.

One of DeLuna’s lawyers, Hector De Peña, believes that DeLuna and Carlos Hernandez robbed the convenience store together (though he offers no specific arguments for the theory and it seems to be contradicted by eyewitness testimony), but “DeLuna was in front of the counter with Hernandez when Hernandez leapt over the counter and stabbed Lopez.” De Peña suggests that DeLuna was afraid to identify Hernandez: “He didn’t want to risk possibly getting hurt in the county jail or even killed on the street.”  DeLuna’s other lawyer, James Lawrence, said “If you tell me they killed the wrong guy, I don’t know”, and that “it still bothers me to this day” that DeLuna refused to identify Hernandez from photos. Lawrence added, “Of course he was guilty.”