He allegedly hunted and killed without mercy.

The U.S. Customs and Border Patrol supervisor accused of being the serial killer who murdered four women and kidnapped a fifth gave investigators a chilling confession in which he detailed how he lured his victims from borderland boulevards to desolate countryside and then shot them in the head, Texas authorities told The Daily Beast.

Juan David Ortiz, 35, a Navy veteran who worked for Border Patrol for a decade, was so intent on snuffing out lives that he killed his last two victims in the hours after the sole survivor of his violent frenzy escaped and went to police, investigators said.

Ortiz allegedly targeted women, one of them transgender, who were driven into prostitution by drugs.

“It appears that he was hunting or seeking out women off the street,” Webb County District Attorney Isidro Alaniz told The Daily Beast on Sunday.

“These women had been working on the boulevards. He was picking them up and taking them out to rural areas, and executing them with a handgun. All of them were shot in the head or face, leaving their bodies right there.”

In one case, Ortiz allegedly ordered a victim out of his vehicle, a white Dodge truck, and then shot her in the back of the head. He executed another victim as she got out of the truck to go to the bathroom, according to court papers.

Ortiz, who was married with children, was off duty when he killed, according to prosecutors, but at least one lawmaker has already raised questions about how such an apparently disturbed person could land a job in a federal law-enforcement agency.

As an intel supervisor for Border Patrol, Oritz specialized in narcotics and human trafficking and was at one point in charge of patrolling I-35, court documents from an unrelated case show. At least one of his alleged victims was later found along that same route.

The murders began Sept. 3, when Melissa Ramirez, 29, was killed. Her mother, Maria Cristina Benavides, told The Laredo Morning Times that her daughter loved her two young children, aged 7 and 3, but had gotten caught up in drugs recently.

Ten days later, 42-year-old Claudine Luera was shot to death. Her sister, Colette Mireles, told the newspaper she had a “contagious laugh” and was “a happy-go-lucky person growing up.” But “sadly, she was an addict,” Mireles said. “Her life took another turn.”

Ramirez’s slaying had left the community shaken, and according to court papers, Luera began to feel frightened after Ortiz picked her up. She “became nervous and began accusing Juan David Ortiz for being the last person seen with Melissa Ramirez,” according to an affidavit filed with a criminal complaint.

Before she could escape, Ortiz followed her out of the vehicle and shot her in the head multiple times, officials said.

Ortiz allegedly tried to strike again the very next day, but his would-be victim got lucky. After getting into his vehicle, she was talking to Ortiz about Ramirez’s mysterious death, and “that’s when she notices that he starts to become angry and agitated, and she wants to get out of the truck,” Alaniz said.

Ortiz pulled his gun on her, but she managed to get away and “broke the case open on these serial murders,” Alaniz said. The woman went to police and provided a detailed description of the gunman.

Investigators were able to use that to identify Ortiz as their suspect, but by then, he allegedly killed again—not once but twice. Within hours of the escape, he allegedly picked up and murdered two victims, whose names have not been released.

Ortiz was arrested in the bed of a truck on Saturday after a dramatic police pursuit. He was arraigned on four counts of murder and one count of kidnapping and held in lieu of $2 million bond.

Investigators said they don’t know why Ortiz killed.

“ There’s really no motive. In his mind, I don’t know what he was thinking. In the mind of a killer, he was justified in what he was doing,” Alaniz said, describing Ortiz as a “cold, calculating murderer.”

Rep. Henry Cuellar (D-TX) said Sunday he met with Customs and Border Protection Commissioner Kevin McAleenan to discuss the need for Border Patrol candidates to “receive the appropriate psychological screening to ensure that no person who is capable of these type of actions is allowed to join or remain in the ranks.”

Ortiz is the second Border Patrol agent in Webb County to face multiple murder charges this year. In April, Ronald Anthony Burgos-Aviles was accused of killing a 27-year-old woman believed to be his lover and the couple’s 1-year-old child. He pleaded not guilty last month and is awaiting trial.

Alaniz said he did not think Ortiz’s alleged crimes reflected badly on Border Patrol. “This individual is acting on his own,” the prosecutor told The Daily Beast.