Inside the hunt into Border Patrol agent who targeted sex workers in killing spree

In September 2018, a border town in Texas was rattled after four women who were sex workers were found dead.

For days, Laredo authorities were hunting down every clue they could after they first discovered the bodies of Melissa Ramirez, 29, and Claudine Anne Luera, 42, who were shot and left on the outskirts of town.

"What kind of person would do this?" "20/20's" John Quiñones asked Capt. Federico Calderon of the Webb County Sheriff's Office, who investigated the homicides.

"A monster," Calderon answered.

But with the help of another sex worker who told police she escaped the suspect, investigators would eventually identify and arrest the "monster," an active U.S. Customs and Border Protection Supervisor.

They would also learn he killed two more victims before he was finally captured: Guiselda Alicia Hernandez Cantu, 35, and Janelle Ortiz, 28.

The "20/20" broadcast “The One Who Got Out,” airing Friday, Nov. 17 at 9 p.m. ET and streaming on Hulu the next day, will explore the murders, the investigation and the criminal trial. It will include emotional interviews with the victims' families and friends, as well as the investigators who brought them justice.

Maria Cristina Benavides, Ramirez's mother, told "20/20" that she had no idea her daughter was working as a sex worker, but was very concerned when she would be away from home for long periods.

"I worried because sometimes she would be out two to three days," she told Correspondent John Quiñones. "I would tell her 'Talk to me, talk to me because I stay waiting for you.'"

Ciara Munguia, Luera's daughter, told "20/20" that she knew what her mother did to earn money, but said that she did it to help her family.

"She wanted us to have a better life--and felt like she couldn't provide that for us, so then she resorted to the streets," Munguia said.

On Sept. 4, 2018, Ramirez's body was found north of Laredo, along a dusty road by a rancher. The victim was reportedly abandoned there and had been shot multiple times, according to Calderon.

"It seemed like an actual execution," he said.

Investigators found .40 caliber shell casings and distinct tire tread marks at Ramirez’s crime scene.

Nine days later, a truck driver found Luera clinging to life in a ditch about a mile from where Ramirez's body was found. She was shot in the head and rushed to a hospital where she later died.

Munguia said her mother was already afraid after news of Ramirez's death and had texted her daughter two days before she was found murdered. Munguia said she was devastated by the images of the site, which was covered in blood.

"Nobody deserves that, nobody. She had such a good heart. She was just the sweetest lady," Munguia said.

Investigators had no luck finding a suspect or the vehicle connected with the killings, but 10 days after Ramirez's body was discovered, investigators caught a major break when another sex worker appeared after fleeing from a truck at a gas station.

Erika Peña, 26, says she ran out of a truck at a gas station to a state trooper who was pumping gas. Peña told the trooper her client, who she knew as "David," had threatened her with a gun to her head before driving off.

Peña gave investigators the make and model of the car and guided them to the house where she said she had been with her client. Police said that inside the home were several firearms including an AR-15 rifle.

Investigators would later find out the home belonged to Juan David Ortiz, a Border Patrol Supervisor who was assigned to help investigators track the killer.

“It was like something out of a movie,” says Maria Salas, who covered the case for the Laredo Morning Times.

Seven hours after Peña was found, officers located Juan Ortiz and his vehicle at another gas station.

After a dramatic chase and standoff, captured on police body cameras, they arrested him in a parking lot at a nearby hotel.

According to investigators, Ortiz, a married father of three and Navy veteran, was evasive and aggressive during his nearly nine-hour interrogation.

Meanwhile, Peña was giving vital information to the officers, who were already making connections between the killings and Ortiz, including the fact that the shell casings discovered at the victims’ crime scenes matched those in his service weapon.

"Little by little, the investigator and the [Texas] ranger are able to confront him with evidence, physical evidence, photographic evidence," Isidro Alaniz, the Webb County District Attorney said.

Eventually, Ortiz admitted that Peña was in his home and told investigators about his anger and resentment towards sex workers.

"I wanted to like clean up the streets and nobody is going to do it," he said.

Ortiz would admit that he solicited Peña and the two other victims. He said he killed Ramirez and Luera and then went home. Ortiz said he used his service revolver to kill Ramirez.

"It kind of took me back because I don't know if you ever see the devil coming out of somebody," Ernesto Salinas, a Texas Ranger who investigated the case, told "20/20."

But Ortiz would reveal there was more to his carnage. In between Peña's escape and his arrest, Ortiz revealed he returned to San Bernardo Avenue and picked up two more sex workers, Guiselda Cantu and a transgender woman named Janelle Ortiz, whom he shared no relation.

Ortiz confessed to killing both sex workers and provided the police with the locations of their bodies.

Janelle Ortiz's family told "20/20" they were devastated when they got the news of her murder.

"She was loved, very loved," said her younger sister Rose Ortiz.

In January 2019, Juan David Ortiz pleaded not guilty to his charges but COVID-19 delayed the start of the trial until Nov. 28, 2022.

"I had lost hope all already when COVID hit," Rose Ortiz, said. "We're not going to get our justice."

Ortiz's attorney, Joel Perez, never denied Ortiz killed the four women, but contended that his client suffered from PTSD and blackouts. The defense never called any witnesses.

In his closing statement, he tried to convince the jury that Ortiz is not a cold-blooded serial killer

Prosecutors, however, presented their evidence linking Ortiz with the killings, including 200 exhibits, and called Peña to testify. They also suggested the defense's claims of blackouts were lies.

Ortiz was convicted on Dec. 7, 2022.

"I had a heavy heart for four years and when I heard it, it just went away,” said Elva Enriquez, Janelle Ortiz's mother. “Finally, I had my justice. And I said, 'Now, you can rot in hell.”

According to District Attorney Alaniz, the victims’ families asked that the death penalty be taken off the table and Ortiz was eventually sentenced to life in prison without parole.

For Munguia, her goal is to move forward the best she can.

"I love to visit my mom and pray to her and affirm her and remind her that we're okay and we're here and we're always going to miss her," she said.

"What life do you think your mother would want you to live?" Quinones asked.

"The life I'm living," Munguia said.

ABC News' John Quinones, Joseph Diaz, Jonathan Leach, Andrew Paparella, Scott Engel and Sunny Antrim contributed to this report.