Alaniz says his office plans to charge Ortiz with four counts of murder and one count of aggravated kidnapping. Authorities say one woman Ortiz had abducted escaped early Saturday morning and she was able to alert authorities.
Webb County Sheriff Martin Cuellar says Ortiz fled from state troopers and was found hiding in a hotel parking lot in Laredo at around 2 a.m. Saturday.
Investigators are still trying to determine a motive for the killings.
Authorities didn't disclose the victims' names or nationalities and they declined to discuss the evidence or say how the women were killed.
U.S. Customs and Border Protection has offered condolences to family and friends of the victims.
CBP says in a statement that while it is the agency's policy not to comment on an ongoing investigation, "criminal activity by our employees is not, and will not be tolerated."
"Out of respect to the victims’ family and friends, we ask that deference and due process be given to the investigation so that all the facts are brought to light and they can receive the closure they deserve," the agency's statement continues. "CBP will provide more information when available."