For 2 1/2 years, Sandra Luz Hernandez, like so many Mexican mothers, searched for her missing son.
Her activism grew steadily over time. She hung posters of her son and others who had disappeared. She led marches through her hometown of Culiacan, in the infamous drug cartel state of Sinaloa. She staged sit-ins outside the governor's office to demand justice. She scoured morgues and clandestine mass graves.
Last week, friends and colleagues say, her activism got her killed. Gunmen leaped from an SUV, put on masks and shot Hernandez dead in broad daylight on a Culiacan street.
"I don't know if she was getting closer" to finding out what happened to her son, said Oscar Loza, head of the Sinaloa Human Rights Commission. "But clearly that's what her enemies thought."
Hernandez, 52, became the latest of dozens of Mexican human rights activists slain in the line of work. The fact that so few of those cases have been prosecuted, or even investigated, has given criminals and corrupt officials carte blanche to eliminate those who challenge their power.
Nearly 30,000 people have gone missing in Mexico in the last seven years of intense violence involving drug gangs, other criminals and government security forces. More than 70,000 have been killed.
Many of the missing were last seen being picked up by security agents, while others fell prey to drug-trafficking and extortion gangs that control large parts of the country, recruiting unwilling workers, or mules, and ultimately killing them.
Hernandez, a mother of five and a snack vendor married to a supermarket night watchman, was an accidental activist.
On Feb. 12, 2012, her son Edgar Garcia Hernandez, then 23, a messenger and clerk at the Sinaloa state prosecutor's office, was seized from his home by gunmen and never seen by the family again.
Devastated, according to her friend and colleague Alma Rosa Rojo, Hernandez began imploring officials to look into the case. Her son was, after all, a government employee, albeit a minor one.
Initially she was told — as so many grieving relatives are, often incorrectly — that he was a criminal. As if that justified his disappearance. It was an easy way for authorities to elude responsibility.
"I don't care," Hernandez told Marco Antonio Higuera, the state prosecutor and Edgar's boss, according to Rojo. "He was my son. I gave birth to him. I love him."
The official indifference, even callousness, in the face of such loss has been a recurring theme in Mexico. Only a handful of state governments have even bothered to take DNA evidence, and families have been forced to travel from morgue to morgue, mass grave to mass grave, in search of their loved ones.
Hernandez eventually came to join a Culiacan activists groups whose members, like Rojo, were looking for missing relatives. Rojo's 47-year-old brother, an agricultural worker, disappeared five years ago.
The group in Culiacan is relatively small; similar organizations now exist in numerous Mexican states, where relatives have to search on their own for family members, doing their own detective work. They usually receive scant support from authorities.
Hernandez may have attracted special attention, Rojo said, because she was so outspoken.
"She was very brave," Rojo said in an interview. "As a mother, she fought day after day," often putting herself aggressively in the face of local officials.
Hernandez was apparently lured to her death. After yet another fruitless meeting with state prosecutors, she received a call from an unknown person offering information on her son. She was directed to the Benito Juarez neighborhood of Culiacan. She went with a friend and was ambushed just off Constitution Street.
"Run! Run!" the friend cried, according to witnesses. The friend escaped, but it was too late for Hernandez, who died instantly of numerous gunshots to the head. Police reportedly recovered 15 spent 9-millimeter casings.
Mexican and international human rights groups have repeatedly urged the government here to investigate, find the missing and prosecute the perpetrators. The government of President Enrique Peña Nieto created a task force amid much fanfare a year ago, but it has shown no progress.
At Hernandez's funeral, dozens of people marched through the streets of Culiacan, wearing white shirts and black ribbons and demanding "justice for Sandra." Police say they have no suspects in the case.
There is little optimism among people such as Rojo. "Because we are poor, we have no right to justice," she said.
As Hernandez put it in a February interview with the Sinaloa newspaper Riodoce: "I am not looking for the guilty ones, for the details, I just want my son.... Please just tell me where he is."