(CNN) -- A Border Patrol agent accused of killing four women in South Texas pleaded not guilty during an arraignment Thursday.
At a court in Webb County, Juan David Ortiz, 35, entered his not guilty plea to a charge of capital murder, one count of aggravated assault with a deadly weapon, one count of unlawful restraint, and one count of evading arrest or detention.
His attorney, Joel Perez, said his client "like any other person charged with a crime, is presumed innocent" and "has a right to a fair jury trial."
Ortiz, a 10-year veteran of US Customs and Border Protection, was arrested last September, after a woman escaped from him and found a state trooper, police said.
After his arrest, Ortiz confessed to fatally shooting four women during the first two weeks of September. The victims have been identified as Melissa Ramirez, 29, Claudine Luera, 42, Guiselda Alicia Cantu, 35, and 28-year-old Janelle Ortiz, who was also know as Nikki Enriquez.
As Ortiz was led out of the courtroom in handcuffs on Thursday, the mother of one of the dead women yelled out in Spanish, "Damn you, you damn murderer," according to Yanira Resendez, a spokeswoman for the Webb County District Attorney's office.
When Ortiz was indicted in December, prosecutors announced they plan to seek the death penalty.
In a statement, Ortiz' attorney said that "in the event of a conviction for capital murder, the law presumes a punishment of life imprisonment rather than death."
Webb County District Attorney District Attorney Isidro Alaniz had said the Texas Penal code allows a lone capital murder count if the defendant carried out multiple murders "pursuant to the same scheme or course of conduct."
He confessed to the killings, police say
In December, Alaniz described Ortiz as a self-proclaimed vigilante who wanted to "clean up the streets of Laredo by targeting individuals he deemed to be disposable and that no one would care about. People he did not give value to."
"In this case," Alaniz said, "he preyed on the weak, the sick and the vulnerable."
He got to know the people he targeted and met with them several times to gain their trust, according to Webb County Sheriff's Department Chief Deputy Federico Garza.
His first victim, police say, was Ramirez. Ortiz told police he picked her up September 3 and drove her out to the edge of the city, where she exited his vehicle to urinate on the side of the road, an arrest affidavit says. Ortiz shot her multiple times in the back of the head and drove away, according to police.
Days before his arrest, Ortiz picked up another woman, Luera, and drove her outside of Laredo. After she became suspicious and accused Ortiz of being the last person seen with Ramirez, Luera got out of the vehicle, the affidavit says.
Ortiz shot her multiple times in the head and fled, police said.
He picked up another woman on September 14, drove to his home in the northern part of Laredo and then took her to a gas station. There, Ortiz pulled out a pistol and pointed it at her, but the woman maneuvered herself out of the car and ran to a state trooper fueling up at the gas station, the affidavit says.
After the woman escaped, the Border Patrol agent picked up Cantu, who would become his third victim. Later, Ortiz picked up a transgender woman and drove her about five miles from where he killed Cantu, the affidavit says.
He ordered her out of the car and shot her once in the back of the head, the affidavit says.
Authorities initially identified the transgender woman as Humberto Ortiz but have since then confirmed that she identified herself as Janelle Ortiz and Nikki Enriquez.
Following the agent's arrest, Alaniz said Ortiz "would go about his daily activities like anybody here. He appeared normal by all accounts and circumstances. At the nighttime, he was someone else, hunting the streets of San Bernardo for this community of people and arbitrarily deciding who he was going to kill next."
Ortiz remains in custody on a $2.5 million bond.