SANTIAGO: As Chile readies to mark 50 years since the 1973 coup against then President Salvador Allende, the country is increasingly asking a question about the thousands who disappeared in the years of military dictatorship that followed: "Where are they?".

The South American country is ramping up a hunt, with a National Search Plan launched on Wednesday by progressive President Gabriel Boric to consolidate the reams of case files and investigations, hoping to unearth new leads.

During the bloody 17-year dictatorship of General Augusto Pinochet, some 40,175 people were executed, detained and disappeared, or tortured as political prisoners, according to the Ministry of Justice, based on fact finding by various commissions.

There are 1,469 people who were victims of forced disappearance, of which 1,092 were detained and disappeared, while 377 were executed and their remains never returned.

"We had the illusion that they were alive, but over the years we realized they weren't," Juana Andreani, a detainee herself during the dictatorship, and a friend of a person who disappeared, told Reuters.

"At least they should tell us what happened to them, what was done to them? That is the worst part of these 50 years."

Chile on Sept. 11 will mark half a century since the coup, part of a wave of military rule in the region in the 1970s that also included Argentina, Brazil, and Uruguay, where families have also pushed to unearth information about the disappeared.

The searches have normally, at best, led to families being given bone fragments identified as their kin who disappeared. Many around the region remain to be found and identified.

In an unusual case earlier this week, a 42-year-old lawyer who was stolen at birth during the Pinochet era and raised in the United States, met his biological mother for the first time after finding her thanks to DNA tracing.

Victims of human rights violations and their relatives say the Armed Forces must have more information that they have not yet provided about the fate of the missing or dead, including pushing for files in the United States to be declassified.

Daily briefings made to then-U.S. President Richard Nixon on Sept. 8 and Sept. 11, 1973, were declassified earlier this week, which show how he was briefed on Chile's unfolding coup.

In Chile there have been dozens of trials and convictions for human rights violations, though Pinochet himself, who died in December 2006 at the age of 91, was never convicted of his responsibility for the crimes.

Many people still want more answers and accountability.

"Obviously the higher ranks of the Armed Forces are responsible. What did they do with the corpses?" said Carlos González, who was detained and tortured by the military during the dictatorship.

"It can't be that we don't know what happened with around 1,000 Chileans. This just can't be."