McALLEN, Texas (Border Report) — A capital murder trial is underway for a former Border Patrol agent accused of killing four women in 2018 in the border town of Laredo, Texas.

The trial against former Border Patrol Agent Juan David Ortiz began Monday and is being held in San Antonio; a judge granted a change of venue from Webb County, where the deaths occurred.

Ortiz, 39, a 10-year veteran of the Border Patrol, is charged with four counts of murder, aggravated assault with a deadly weapon and unlawful restraint.

Prosecutors have called Ortiz a “vigilante” who targeted those involved in drugs and prostitution, KENS5 reported Monday.

The body of Melissa Ramirez, 29, was found on Sept. 3, 2018. The body of Claudine Luera, 42, was discovered 10 days later on Sept. 13 about 2 miles from Ramirez’s location. The bodies of Humberto “Janelle” Ortiz, 28, and Guiselda Cantu also were found, which prosecutors say are linked to former agent Ortiz.

On Sept. 14, 2018, Erika Pena, alleged that Ortiz “pointed a firearm” at her, according to an affidavit, and she said she escaped from Ortiz and she flagged down a Texas state trooper.

On the opening day of the trial on Monday, Pena testified that she had been involved in prostitution and had taken drugs, including heroin, in front of Ortiz. She said she went with him to his Laredo home. After they were in his truck where he “pulled out a gun at me.”

On the witness stand, she pointed her left hand to her head in the shape of a gun and said that is where the gun was pointed at her head “next to my face,” she testified.

“I took off running. I snapped,” Pena testified. She said she just had a feeling that he was somehow connected to the recent deaths of these women.

“Someway somehow I took off running without out a shirt,” Pena testified. “He was trying to grab me by my left shoulder … he just pointed it (gun) right at me.”

She said she was “nervous, shaking,” after the escape. She said she tried to escape from his truck after Ortiz’s demeanor changed when she began to talk about Ramirez, one of the victims.

“Everything happened so fast,” she said. “I run to the store and there’s a trooper putting gas.”

Pena said she went up to the Texas state trooper and “I told him someone had just pulled out a gun at me.”

The affidavit states that trooper Francisco Hernandez was at the gas station around 9 p.m. that evening “when he was approached by a shirtless adult female asking for help.”

According to the affidavit, Pena helped authorities to locate Ortiz’s home. They found his vehicle at another gas station around 1 a.m. the next morning, Sept. 15, but he “fled on foot.” Ortiz was found an hour and a half later and arrested “hiding” in the parking garage of a hotel, according to the affidavit.

The affidavit claims that after he was arrested, Ortiz verbally confessed to killing four women between Sept. 3-15, 2018.

Pena also testified that another victim, Janelle Ortiz, was her “best friend” and also was involved in drugs and sexual activities.

After a lunch break, the trial resumed with testimony from trooper Hernandez who encountered Pena after she said she fled.

Video footage from Hernandez’ body camera was played for the court showing Pena shirtless repeating her story, shaking and repeatedly asking for help and protection.