The full human cost of Mexico'sbloody drug war during the last six years is only now becoming apparent. Nearly 70,000 people died and more than 26,000 went missing between 2006 and 2012. A scathing new report by Human Rights Watch casts substantial blame for the problem on the country's security forces, which it says have not only been implicated in many of the underlying crimes but have failed to adequately investigate claims by friends and family members of the victims. The result, the report says, is the "most severe crisis of enforced disappearances in Latin America in decades."

Human Rights Watch researchers looked into a few hundred cases and confirmed 149 examples of enforced disappearances by security forces. They described a pattern in which uniformed soldiers or police detain people without arrest orders or probable cause — at their homes, in front of family members, at checkpoints or in public settings. The arrests are almost never officially registered and the arrestees are not turned over to the prosecutor's office, as required by law. When relatives arrive to ask about the detainees, the report said, "they are told that the detentions never took place."

These are familiar allegations. But Human Rights Watch also shows how the authorities fail to follow up or investigate — declining to trace cellphones or obtain footage from security cameras or track the bank transactions of the disappeared.

It now falls to President Enrique Peña Nieto to address the crisis of the disappeared. Clearly, there is no single solution to the problem of drug violence and impunity in Mexico; myriad reforms are needed. But a good and simple place for the new administration to begin is to create a central and accurate database of missing people and unidentified remains. Those records would provide an important resource for prosecutors, police and family members of those who are missing.

Until late last month, there was only an unofficial list of names, which has since become public. Before that, local authorities who received reports about disappearances could share information only by calling individual agencies in other states. Often, they simply failed to do so.

The list of missing persons is still too vague, often failing to include basic information such as age, height or even scars. The registry should be expanded to include a more comprehensive profile, including DNA samples of family members. That information could then be used to test against unidentified human remains, including those found in recent years in mass graves.

The United States has pledged nearly $2 billion in aid since 2007 to help Mexico fight a shared drug war. The Obama administration should encourage the new government to ensure that the database is up and running quickly, and that the disappearances are fully investigated.