A former Border Patrol agent who confessed to killing four sex workers in 2018 has been convicted of murder after jurors heard recordings of him telling investigators he was trying to “clean up the streets” of his South Texas hometown.

Juan David Ortiz, 39, receives an automatic sentence of life in prison without the possibility of parole because prosecutors decided not to seek the death penalty.

Ortiz, a Border Patrol intelligence supervisor at the time of his arrest, was accused of killing Melissa Ramirez, 29, Claudine Anne Luera, 42, Guiselda Alicia Cantu, 35, and Janelle Ortiz, 28.

Juan David Ortiz reacts in court
Juan David Ortiz confessed to killing four women in South Texas (Jerry Lara/The San Antonio Express-News/AP)

Their bodies were found along roads on the outskirts of Laredo in September 2018.

During the trial that began last week, jurors heard Ortiz’s confession during a lengthy taped interview with investigators.

Ortiz told investigators he had been a customer of most of the women, but he also expressed disdain for sex workers, referring to them as “trash” and “so dirty” and insisting he wanted to “clean up the streets”.

He said “the monster would come out” as he drove along a stretch of street in Laredo frequented by the women.

Following the verdict, family members of the victims faced Ortiz to give their statements.

Ms Ramirez’s sister-in-law, Gracie Perez, said she was “a loving, kind and funny person”, adding that the hearts of the dead woman’s children are now broken.

“Do you know how much pain you have caused this family?” Ms Perez said.

“My heart is torn apart knowing that I won’t be able to see her but to visit her in the cemetery.”

Webb County Medical Examiner Corinne Stern testified that Ms Ramirez, Ms Luera and Ms Ortiz were fatally shot while Ms Cantu, who was shot in the neck, died of blunt force trauma to the head.

The bullets collected from the crime scenes came from the same gun, and matched the weapon found in Juan David Ortiz’s vehicle, a ballistics expert testified.

Ortiz served in the US Navy for nearly eight years until 2009, holding a variety of medical posts and served a three-year detachment with the Marines.