The skeletal remains of 12 people found earlier this year close to Mexico’s Ciudad Juarez have been identified as female, bringing attention once more to the city’s high rate of murders against women.

Mexican authorities announced Monday that six of the 12 victims discovered in January and February in Juarez Valley have been identified as girls between the ages of 15 and 19 years. The girls had been missing since 2009 and 2010, reports the LA Times. The other six have also been identified as female, though their ages are unknown.

The cause of death remains unclear, as little more than the bones have been found.

Activist leader Victoria Caraveo of the NGO Women of Juarez (Mujeres de Juarez) told the Associated Press that the discovery suggests the work of a “well-organized gang … with some people kidnapping them, others mistreating, using or raping them, and others dumping the bodies.”

InSight Crime Analysis

Ciudad Juarez has been afflicted by a high rate of “femicides” (gender-based killings of women) over the past two decades. More than 500 cases have been documented since 1993, though the actual number may be far higher. The authorities have generally failed to bring about any prosecutions, and activists protesting the lack of action by Mexico’s government have become targets, as evidenced by the rape and murder of campaigner Susana Chavez in January 2011. In November last year, the government was forced into making an apology for the state’s failure to prevent the killings, and the continued impunity.

The motives behind the murders of women are often unclear, though they are thought to be driven in part by the macho culture linked to the drug trade, and the resulting violence that has engulfed Ciudad Juarez in recent years.

What’s more, Mexico’s criminal gangs have increasingly moved into human trafficking, increasing the levels of violence against women. According to Mexican congresswoman Rosi Orozco, there are some 800,000 cases of sex trafficking in the country each year. Ciudad Juarez’s location as a border town and key transit point for people and goods moving north to the US increases the potential for violence associated with these trades.

Based on a recent report by the Small Arms Survey entitled “ Femicide: A Global Problem,” while Mexico overall has a low rate of femicide compared to others in Central America, with 2.5 cases per 100,000 people between 2004 and 2009, the rate in Ciudad Juarez stood at 19.1 per 100,000 in 2009.