Prosecutors say a federal agent working for the U.S. Border Patrol confessed to killing four sex workers over a two-week period. The suspect remains in jail on a $2.5 million bond.

Supervisory Border Patrol Agent Juan David Ortiz remains in the Webb County jail on four counts of murder relating to the deaths of sex workers in the Laredo area. Webb County officials referred to the case as the work of a serial killer, KGNS reported from Laredo on Monday.

According to an affidavit obtained by the local news outlet, Ortiz confessed to killing all four sex workers. The killing spree allegedly began on September when Ortiz said he drove 29-year-old Melissa Ramirez to a location near Camino Colombia. He said he got the woman out of this truck and then shot her in the head multiple times, the news outlet reported.

Ten days later, a truck driver found the body of victim number two, 42-year-old Claudine Luera. The driver found the body a few feet from where Ramirez died. Ortiz said he pulled over to the side of the road after she questioned him about the death of the first victim. He then allegedly got out of his vehicle and shot her in the head multiple times.

One woman escaped death during her encounter with Ortiz. She alerted police who caught up with Ortiz at about 2 a.m. Saturday morning. He had kidnapped the woman but she managed to escape before he could take her life. She is the only person known to have survived Ortiz’s killing spree, officials reported.

Court documents state that the surviving victim confronted Ortiz about the first victim at his home. He then drove her to a gas station where she managed to contact Texas Department of Public Safety troopers about his location. Ortiz fled before troopers arrived and killed two more people, investigators explained.

Police took Ortiz into custody at about 2 a.m. Saturday morning. A short time later, police found Ortiz’s third victim. The fourth victim, a transgendered female, was found later that day.

On Monday afternoon, law enforcement officials in Webb County released the identity of Oritz fourth victim, the Houston Chronicle reported. Police say the victim was 28-year-old Humberto Ortiz, a transgendered woman. Officials have not yet released the identity of the third sex worker.

In total, Ortiz reportedly confessed to the murder of the four sex workers and the kidnapping of the surviving victim.