CIUDAD JUAREZ, Mexico (AP) — Forensics tests have confirmed that 12 sets of skeletal remains found near the US border are those of girls and women, authorities announced yesterday, fueling fears that young women in the Ciudad Juarez area may once again the targets of serial slayings.

The sets of bones were found in January and February in fields in the Juarez valley, east of Ciudad Juarez, and experts have discovered an alarming similarity in the victims’ ages. Of those for whom identities have been established, two were 15 years old, one was 16, two were 17 and one 19.

The special prosecutors’ office for crimes against women in northern Chihuahua state did not immediately identify the cause of death in the cases, in part because little but bones were found. The remains were in such bad condition that experts have not yet established whether some of the bones might belong to additional victims.

Three of the 12 bodies had previously been identified as women’s, but the gender of the other nine bodies was established by DNA and forensics tests.

Ciudad Juarez, across the border from El Paso, Texas, was the scene of a series of eerily similar killings of more than 100 women, most of them young, beginning in 1993. Those possible serial or copy-cat killings, with similar victim profiles and killing methods, appeared to taper off by late 2004 or early 2005.

But Victoria Caraveo, the leader of the activist group Women of Juarez, said the new discoveries could mean that an entire band of killers may be at work.

“This could be a well-organised gang,” Caraveo said, “with some people kidnapping them, others mistreating, using or raping them, and others dumping the bodies,” Caraveo said.

The DNA profiles matched those of six women and girls who had been reported missing in 2009 and 2010. Some had reportedly left home, while another was on her way to work at a border assembly plant, or maquiladora. The identities of the other six victims are still under investigation.

In the cases from 1993 to 2004, the victims were usually young, slender women, often maquiladora workers, who were abducted, often sexually abused and strangled before their bodies were dumped in the desert.

Caraveo said one thing is the same as in the previous cases. She said authorities have failed to conduct thorough, timely investigations into women’s disappearances, both then and now. She said that, so far in 2012, 18 young women have disappeared in Ciudad Juarez.

The failure of state officials to solve the earlier crimes led to creation of a special federal prosecutor’s office to probe those and similar killings.

In November, the Mexican government formally apologised for having failed to protect some of the victims of the earlier killings.