The vast majority of human rights abuses allegedly committed by soldiers waging Mexico's war on drug gangs go unsolved and unpunished despite reforms letting civilian authorities investigate and prosecute such crimes, a report said Tuesday.
The Washington Office on Latin America study, described as the first comprehensive analysis of military abuse investigations handled by the Attorney General's Office, found there were just 16 convictions of soldiers in the civilian judicial system out of 505 criminal investigations from 2012 through 2016, a prosecutorial success rate of 3.2 percent.
Moreover, there were only two "chain of command responsibility" convictions for officers whose orders led to abuses, it said.
The report said factors that hinder civilian investigations of the military include parallel civilian and military probes, limited access to troops' testimony and soldiers tampering with crime scenes or giving false testimony.
"This militarized public security model has negatively impacted Mexico's criminal justice system. The civilian justice system faces challenges — including military authorities' actions resulting in the obstruction or delay of investigations — which limit civilian authorities' ability to sanction soldiers implicated in crimes and human rights violations," the group said.
The Attorney General's Office, the Defense Department and other government offices did not immediately respond to requests for comment.
The military has played a central role in the war on drug cartels since at least late 2006, when newly installed President Felipe Calderon deployed soldiers across the country to fight the gangs. The militarized offensive has continued under current President Enrique Pena Nieto.
During that time there have been numerous accusations of serious human rights violations by soldiers, such as torture, killings and forced disappearances.
Critics say the Mexican military is not trained to carry out policing activities. However, many police departments in the country are seen as corrupt, outgunned and even in cahoots with organized crime gangs, and thus unreliable allies against the cartels.
One high-profile rights case involving the military was the 2014 killing of 22 suspected criminals by soldiers in the central town of Tlatlaya. The military initially claimed they died in a fierce firefight, but evidence suggested there was no protracted shootout and some of the dead appeared to have been executed.
Seven soldiers were accused of homicide, but the charges were thrown out by civilian courts due to lack of evidence. In August of this year, a judge ordered an investigation into whether army commanders played any role in the killings.
The report said Tlatlaya is an example of a case in which military investigators had access to the crime scene and soldiers' testimony before civilian authorities.
"The Tlatlaya case illustrates that holding military and civilian investigations concurrently delays and obstructs justice ... [and] shows that in military jurisdiction, cases of grave human rights violations also go unchecked or remain unpunished," the report said.
Reforms in 2014 changed how allegations of abuses by the military can be investigated, including the right to conduct a civilian probe in such cases and for victims to participate.
Among the 16 successful prosecutions of soldiers carried out by the Attorney General's Office are convictions for the cover-up of a human rights violation and desecration of a corpse; forced disappearance; homicide; injuries and trespassing, and rape, the report said.
The two "chain of command" convictions the study found were of a lieutenant colonel and a second lieutenant in two forced disappearance cases in in the northern states of Chihuahua and Nuevo Leon.
The Washington Office on Latin America said the report was based on three main sources: interviews with human rights groups and lawyers, right-to-information requests that yielded information including on convictions of soldiers, and collaboration with journalists who created a website on the issue, Cadenademando.org (Spanish for "chain of command").
It added that it was "possible" there may have been more convictions than the 16 it documented, but authorities did not report them in response to right-to-information requests.
The United States has supported Mexico's security efforts through the multibillion-dollar Merida Initiative, including outfitting the military with helicopters and training security forces. According to the report, more than $521 million in counter-drug assistance has flowed from the U.S. Defense Department to the Mexican military since 2008.
The report calls for measures from both Mexico and the United States to bolster the Mexican judicial system. It also urges Washington to condition aid money on improvements in the human rights record of Mexican security forces and to enforce U.S. laws barring funding of units known to have committed gross rights violations.