A Texas prosecutor has charged a U.S. Border Patrol supervisor with four counts of murder following a two-week killing spree that left four female sex workers dead and ended only when a fifth woman escaped from him at a gas station and found help.Texas state troopers arrested Juan David Ortiz, 35, an intel supervisor for the Border Patrol, Saturday after he fled from state troopers and was found hiding in a truck in a hotel parking lot in Laredo around 2 a.m. Saturday, Webb County Sheriff Martin Cuellar said at a news conference in the border city about 145 miles (235 kilometers) southwest of San Antonio. Cuellar said investigators have “very strong evidence” that he is responsible for the deaths of the four women working as prostitutes. One of the victims was a transgender woman, said Webb County District Attorney Isidro Alaniz. “We do consider this to be a serial killer,” Alaniz said. Ortiz has also been charged with aggravated assault and unlawful restraint of a fifth woman who escaped from him and found a state trooper.Alaniz told The Texas Tribune that after the suspect picked up the fifth woman she quickly realized that she was in danger. “When she tried to escape from him at a gas station that’s when she ran into a (state) trooper,” Alaniz said. He said that authorities believe Ortiz had killed all four women since Sept. 3. The names of the victims were not immediately released. Alaniz said two of them were U.S. citizens but the nationalities of the other two were not yet known. But both Alaniz and Cuellar declined to discuss the evidence or say how the women were killed. Alaniz said investigators are still trying to determine a motive for the killings. Cuellar said investigators believe Ortiz acted alone. “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,” Alaniz said. Ortiz was a 10-year veteran of the Border Patrol. U.S. Customs and Border Protection issued a statement saying that it was fully cooperating with the investigation. “Our sincerest condolences go out to the victims’ family and friends. While it is CBP policy to not comment on the details of an ongoing investigation, criminal action by our employees is not, and will not be tolerated,” the agency said.. The Texas Department of Public Safety, whose Texas Rangers are investigating, did not return several messages seeking comment.