The number of illegal firearms seized by Mexican authorities dropped by more than 60 percent between 2013 and 2016, according to Milenio.

Citing data from the Defense Department (Secretaría de la Defensa Nacional), the news outlet reported on June 15 that seizures stood at 9,474 in 2013, but only 3,593 in 2016.

Nearly 28,000 illegal weapons were seized between December 2012, when President Enrique Peña Nieto took office, and May 2017. A total of 3,324 of grenades were also taken out of circulation during that period. Grenade seizures decreased by nearly 70 percent between 2013 and 2016, however.

These figures indicate that Mexican authorities seized an average of 17 weapons and 2 grenades per day since Peña Nieto took office. The majority of these firearms were high powered weapons.

A separate report by Animal Político noted that the number of investigations for carrying or stocking illegal firearms dropped steeply between the first four months of 2015 and those of 2017, while the number of cases opened for gun-related homicides during those same periods increased by 70 percent, numbering 5,075 cases between January and May 2017.

The study suggests a correlation between the decreasing illegal firearms investigation and the rising number of gun-related homicides since 2015. The report also notes that several Mexican states with the highest rates of open investigations into illegal weapons possession -- such as Baja California, Michoacán and Sinaloa -- are also areas with high homicide rates.

InSight Crime Analysis

The reports are not positive, but the greater issue concerning Mexico's weapons black market may be the sheer number of illegal weapons available, rather than a percentage decrease in the small quantity of weapons taken off the black market in recent years.

Assessing the number of available illegal weapons is inherently complicated, but approximates over the years have repeatedly indicated that Mexico's black market holds millions of firearms. In a 2015 report, for example, the country's legislature estimated that 13 million out of 15 million firearms in circulation were illegal.

Mexican cartels have also been largely successful in acquiring military-grade weapons over the years. Criminal elements sometimes have superior firepowerthan security forces, and seizures also indicate a steady sophistication of criminals' arsenals.