First, there were just a few bones and body parts, found in a valley beyond the sprawl of this wild city. At least four women had been killed and dumped, the authorities said. Then, in the same area, investigators made another discovery early this year: a dozen more dead women and girls. Most disappeared in 2009 and 2010, and when last seen alive many were teenagers, good students with bright smiles of possibility. In death, however, they have become apparitions. Idalí Juache’s mother still insists her daughter is missing, though the police linked her DNA to cranial fragments in the valley’s grave. Elvira González said she felt what seemed like her daughter’s spirit at home, before finding out she had been dumped in the grave. “I never believed this was how she would be brought back to us,” Ms. González said, fighting tears in her modest kitchen. “I always believed she’d be given back to us alive.” Ciudad Juárez became infamous for a wave of attacks beginning in the 1990s that left hundreds of women dead over the course of a decade. International attention moved on, but the killings have continued, with a second wave even larger than the first. Even as overall violence here declines, new clusters of slain women are continually being discovered. Roughly 60 women and girls have been killed here so far this year; at least 100 have been reported missing over the past two years. And though the death toll for women so far this year is on track to fall below the high of 304 in 2010, state officials say there have already been more women killed in 2012 than in any year of the earlier so-called femicide era. This time, though, the response has been underwhelming. “People haven’t reacted with the same force as before,” said Gustavo de la Rosa, a human rights investigator for Chihuahua State. “They think it’s natural.” Mexican authorities have made promises to prioritize cases like these for years, and in the wake of international pressure, prosecutors now argue that more of the killings are being solved. But arrests and convictions are exceedingly rare. For the victims found in the mass grave in the Juárez Valley, even the most basic details were still a mystery months later: forensic teams said they were not even sure how many women were buried there. To many, these women are now part of what looks like a slaughter with peaks and valleys, but no end. In the state office opened a few years ago to investigate violence against women, desks are perpetually covered with stomach-turning case files. “It’s a more vulnerable group,” said Hector Hawley, the forensics investigator charged with documenting the crime scenes of most of the women killed in Ciudad Juárez. “These are not people we expect to see killed.” Mr. Hawley has been working murder cases since 2003. He started specializing in women in recent years, and in his view, the stunning tally of women killed is mostly caused by the increased local involvement in gangs and drugs; and jealous men. Often, both gangs and jealousy come together in a single case. He opened a file on his computer showing one of the 18 women killed in April. Photographs showed that she had been dumped in a public street, and found around 8 a.m. “She was stabbed 63 times,” Mr. Hawley said. Her pink shirt, featuring an image of a heart, was stained with blood. Based on the number of stab wounds, he said, “The killer had to be on drugs.” He opened another file, showing a woman, shot dead, at the bottom of a garbage pile. “She was pregnant,” he said. “We think she owed her bosses money for something, drugs maybe.” He clicked through several other cases showing women young and old, mostly shot and killed at close range. He and two investigators in his office said they did not have any specific information about the women found in the mass grave, but they warned against seeing their deaths as the product of a single cause. “In Juárez, there’s everything,” Mr. Hawley said. “There are jealous husbands, jealous fathers-in-law, there are women killing women.”