In September, Judge Randy Crane of the Federal District Court in McAllen, Tex., dismissed claims of negligent hiring and supervision of Mr. Manzanares filed by the two women who were the victims of his initial attack. The judge concluded that supervisors had not been alerted to any problem in the agent’s background and had no reason to know that anything was amiss. But he allowed claims filed by the 14-year-old girl, now 18, whose ordeal had gone on well into the night — and might have been prevented if Mr. Manzanares’s actions had been detected earlier — to proceed.

The case will drag out for months, however. Judge Crane suggested recently that he was prepared to allow appeals of some of his previous rulings to proceed before the case goes to trial.

Lawyers for the three women presented evidence that Mr. Manzanares’s supervisors failed to notice or intervene when the agent ignored his duties for hours, and failed to thoroughly inspect his truck when he returned at the end of his shift. If they had, the evidence showed, they would have seen it contained used duct tape, blood and discarded restraints.

Mr. Manzanares, a father of two, had no major disciplinary infractions during his six years with the agency, which he joined in 2008 after serving with the United States Army in Afghanistan and working as a jailer for the Hidalgo County Sheriff’s Department. But according to court documents, he appeared to have become a pedophile, and one of the issues in the lawsuit has been whether the Border Patrol should have conducted the kind of employee reviews that would have brought that to light.

In late 2013 and early 2014, he was in the midst of a divorce, living in an apartment in the border city of Mission with his two dogs. Even among his neighbors — more than two dozen of his Border Patrol colleagues lived in the same gated complex — Mr. Manzanares largely kept to himself.

His rampage that day might never have been discovered had the older woman left for dead after the initial attack not come across a Customs and Border Protection officer as she emerged from the brush.

She was still bleeding, and clearly terrified.

The man who did this to her and her daughter, she told the officer, was “dressed just like you.”