A US border patrol agent accused of murdering four women in Texas killed his last two victims in the five hours leading up to his arrest, according to court papers.

Juan David Ortiz, 35, was identified as a suspect in the early hours of Saturday morning after another woman managed to escape from his Dodge truck and alert authorities in the city of Laredo.

She told officers how a man she knew as "David" had picked her up and taken her back to his home, where they discussed the recent murder of her friend — the first victim, Melissa Ramirez.

The conversation continued as they left the house and drove out towards the city limits.

Then, while they were at a petrol station, Mr Ortiz pulled out a pistol, pointed at her and grabbed hold of her shirt.

The woman, named in the affidavit as Erika Pena, said she pulled off her top, jumped out of the truck and ran to a state trooper who was refuelling at a nearby pump.

Texas Rangers identified Mr Ortiz's home and issued an alert with a description of his vehicle just after midnight on Saturday 15 September.

The truck was spotted an hour later at another petrol station, but Mr Ortiz ran off towards a nearby hotel.

At 2.30am he was found hiding in the bed of a truck at the hotel parking garage.

During questioning he confessed to not only attacking Erika Pena but also murdering Melissa Ramirez and three other women between 3 and 15 September, according to reports.

According to Mr Ortiz, he picked up Ms Ramirez, a 29-year-old mother-of-two, along San Bernardo Avenue, a street lined with shops selling goods imported from Mexico.

He told investigators he shot her in the head after they stopped on Highway 255 outside the city limits. Ms Ramirez's body was found the next day, 4 September.

Her mother, Maria Cristina Benavides, told the Laredo Morning Times her daughter was "always smiling".

“I hurt a lot," she added. "All I want is justice. I want that guy to die in jail for taking the life of my daughter."

On 13 September, Mr Ortiz picked up 42-year-old mother-of-five Claudine Ann Luera on San Bernardo and drove her out to the same motorway.

He said he shot Ms Luera when she accused him of being the last person to have seen Ms Ramirez, and got out of his truck. She was found seriously injured off the same highway on Thursday morning and died in hospital the same day.

"She was a happy-go-lucky person growing up," said Ms Luera's sister, Colette Mireles. "She chose the street life. It’s just sad that her habits got the best of her, that life got the best of her."

After Erika Pena escaped on the night of 14 September, Mr Ortiz went on to kill two more women in the five hours before his capture.

He told investigators he picked up an unknown woman and took her to Interstate 35 outside Laredo before shooting her several times in the head, according to the affidavit.

Mr Ortiz then returned to the city and picked up a transgender woman before taking her to gravel pits near the same highway.

"The manner in which they were killed is similar in all the cases from the evidence," said Webb County District Attorney Isidro Alaniz.

"It’s interesting that he would be observing and watching as law enforcement was looking for the killer, that he would be reporting to work every day like normal.

"In our opinion he is the sole person responsible for this horrific serial killing spree."

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Mr Alaniz told the Daily Beast Mr Ortiz appeared to have "hunted" women on the street before taken them to rural areas and "executing them with a handgun".

Mr Ortiz was a Navy veteran who had worked as a supervisor for Customs and Border Protection for ten years.

He specialised in narcotics and human trafficking and was at one point in charge of patrolling Insterstate 35, according to court documents.

Earlier this year another border patrol agent, Ronald Anthony Burgos-Aviles, 29, was accused of murdering his 27-year-old lover and their one-year-old child.

Two others agents in the Laredo sector were arrested in April. David Villarreal, 32, was accused of sexually assaulting a woman while Luis Enrique Aranda, 24, was alleged to have pawned his government-issued night vision equipment.

Texas congressman Henry Cuellar said he had spoken to the Commissioner of US Customs and Border Protection about the recruitment of border patrol agents.

"We have agreed to work together on the hiring and professionalism of border patrol agents.

"We spoke about how more steps need to be taken to make certain that people who want to become border patrol agents 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."

Mr Ortiz has been charged with four counts of murder as well as aggravated assault and unlawful restraint and is being held in jail on a $2.5m (£1.9m) bond.