In early March, Gladys Tordil told a Prince George's County judge that her husband had repeatedly threatened to kill her and that she feared for her life and those of her daughters. After the court granted her a temporary protective order against Eulalio Tordil, an officer with the Federal Protective Service, Mr. Tordil's employers stripped him of his badge and service weapon and put him on administrative duty, as required by federal law.

Two weeks later the court issued another, final protective order against Mr. Tordil that directed him to surrender all firearms in his possession. The Prince George's County sheriff's office responded by confiscating seven more guns listed on the order based on Ms. Tordil's recollection of the firearms her husband owned.

But none of those precautions were enough to save her life. On Friday, police say Mr. Tordil confronted his wife in a high school parking lot where she had gone to pick up their daughter after band practice and fatally shot her as she sat in her car. It was the start of an overnight rampage during which authorities say Mr. Tordil shot five more people, two of them fatally, before being captured by police in neighboring Montgomery County the next day.

Why did Maryland's laws aimed at protecting domestic violence victims, widely regarded as some of the strongest in the nation, fail with such tragic consequences in Ms. Tordil's case?

Mr. Tordil, who on Monday was ordered held without bond, was a bully and a household tyrant, his wife said in requesting the protective order. He demanded that his step-daughters submit to military-style discipline, obeying his commands without question. When they didn't, the punishment could be push-ups or “detention in a dark closet,” she told the court.

Ms. Tordil told the court her husband once hit her so hard he broke the glasses on her face during an argument. For at least a decade, she said, he routinely threatened harm to her and her daughters if she tried to leave.

Yet despite a 2009 Maryland law that requires judges to confiscate an abusive partner's firearms when a final protective order is issued, the courts remain limited in what they can do to ensure the safety of domestic violence victims. That's because most domestic violence cases are heard in family court, a part of the civil court system, rather than in criminal court, where the standard of evidence is much higher. As a result, while civil court judges can issue protective orders and require abusers to surrender their firearms, they are often unable to enforce those orders effectively.

That appears to be what happened in Ms. Tordil's case. The Prince George's County sheriff's office collected all the firearms that Ms. Tordil told the court her husband owned, but the officers had no way of knowing whether her husband also had other weapons not listed in her protective order. Nor could they obtain a warrant to search for other weapons because the standard of evidence that would have automatically triggered a police investigation into the matter wasn't met by the protective order. Moreover, the sheriff's office had no way of preventing Mr. Tordil from buying another weapon, either legally or illegally, after he surrendered his personal firearms. Authorities had to take Mr. Tordil's word that he had turned in all his guns as required.

On Monday, Montgomery County prosecutors said Mr. Tordil had purchased the 40mm handgun he is accused of using to kill his wife legally in 2014. It's unclear why the purchase didn't show up when authorities checked to confirm he was telling the truth about his weapons; how that happened will surely be a focus of the current criminal investigation. But whatever we might learn, it will be too late for Ms. Tordil.

Instead we are left with the paradoxical situation in which the law in this case was scrupulously applied precisely as intended and authorities used it to do everything they were supposed to do to protect the potential victim. Yet in the end none of it was enough to prevent the tragedy that everyone feared.

What can be done to prevent another case like this? Better nationwide regulation of firearms would help by improving the chances that authorities confiscate all guns owned by a potential abuser, but so would better options for threatened spouses to seek protection beyond a court order. The resources to escape abuse are woefully inadequate, and the consequences are deadly.