On August 25, 1974, Rosendo Radilla went missing after he was detained by soldiers in the southern Mexican state of Guerrero, while travelling with his young son.
Forty one years on the Mexican government has offered a 1.5 million-peso ($900,000) reward for information leading to his whereabouts, or to the apprehension of those responsible for his disappearance.
"Disappearances, like the case we have before us, are not resolved until we determine where a person is," the deputy attorney general for human rights, Eber Betanzos, told VICE News. "Just because so many years have passed, doesn't mean that all the lines of investigation have been exhausted."
There are currently more than 25,000 people officially missing in Mexico, an undetermined but significant number of them enforced disappearances involving agents of the state.
The Radilla case stands out thanks to the persistence of his relatives and an Inter-American Court of Human Rights ruling that has turned the case into a symbol of the way that unresolved disappearances can continue to haunt governments decades after the victims went missing.
The announcement of the reward, on October 12, also comes at a time when the government is under unprecedented national and international pressure to stop minimizing the phenomenon.
Last week the UN High Commissioner for Human Rights visited Mexico and met with President Enrique Peña Nieto as well as victims of rights violations, including relatives of people who were forcibly disappeared.
"The failure of the police, and of the justice system, to clarify the whereabouts of the victims and what happened to them, and above all of successive governments and the political system as a whole to stop these crimes is not just regrettable, it is deeply tragic," Zeid Ra'ad Al Hussein said in a press conference in Mexico City.
The current spotlight on Mexican disappearances owes much to the outrage unleashed by the case of 43 student teachers from the Ayotzinapa college in Guerrero who went missing a year ago. They disappeared after being attacked by police in the city of Iguala, in another part of the state.
Radilla's disappearance serves as a chilling reminder of how long the phenomenon has been going on in Mexico, and how often key cases involve Guerrero.
Radilla went missing in the context of Mexico' so-called Dirty War against leftists within a wider army crackdown on the guerrilla movements that emerged in Guerrero and other states in the 1960s and 70s. One of the main guerrilla leaders was Lucio Cabañas, a former Ayotzinapa graduate who was killed by the army in 1974.
According to the testimony of Radilla's 11-year-old son, who was not disappeared, the soldiers accused his father of writing songs supporting the rebels. Fellow detainees would later say they last saw Radilla in the military barracks in his home town of Atoyac de Alvarez on the Guerrero coast.
The Association of Relatives of Detainees, the Disappeared and Victims of Human Rights Violations, known as AFADEM, claims that around 450, of more than 800 people disappeared in the Dirty War, came from Atoyac. The organization is headed by Radilla's daughter, Tita.
Already considered a test case, the Radilla case took on even more significance after a ruling by the Inter-American Court on Human Rights in 2009 that condemned the grave human rights violations of the time, and ordered the sitting government to start actively looking for him and for those responsible for his disappearance.
Julio Mata, an activist at AFADEM, told VICE News that the authorities have failed to comply with the ruling.
"For us there is a chain of impunity where there is no punishment and they continue committing crimes," Mata said. "Nothing really happens. There are no trials, not even an investigation."
The reward now offered by the government for information, he added, is just another whitewash. "The government likes to appear like they are actually doing something, so that they can minimize their responsibility."
The reward comes two and a half weeks after the government announced the creation of a special division of the attorney general's office dedicated to cases of disappearance. According to Betanzos, of the attorney general's office, the new division will be staffed by "specialized investigators who are sensitive to this specific issue," as well as equipped with "advanced technology and methods to locate people."
Betanzos also emphasized the government's support of a proposed new law on enforced disappearances currently in the Mexican Senate.
Such cases are always particularly uncomfortable for the government, and never more so than when they involve the military that has traditionally been viewed and treated as untouchable in Mexico.
The parents of the disappeared students in the Ayotzinapa case and human rights experts have spent months pushing unsuccessfully for a full investigation into the role the military played in the events. They point to documented evidence of the presence of soldiers monitoring the attacks on the students, as well as the army's dirty war history augmented by more recent cases of people who were last seen in the company of soldiers.
General Salvador Cienfuegos, the country's defense minister, made his resistance to the idea of more investigation clear in an interview broadcast on the Televisa TV network earlier this month. "I will not allow them to treat my soldiers like criminals," he said.
In photo above, taken in 1974, Mexican soldiers take a break from searching the mountains for guerrilla leader Lucio Cabañas.
Follow Andalusia Knoll on Twitter: @andalalucha