There are now almost 100,000 people missing in Mexico, according to figures released by the National Search Commission.
The majority have disappeared amid the drug war violence of the past decade and a half, with most being killed by drug cartels and dumped in unmarked graves.
Family members across the country have taken on the task of searching for their missing loved ones themselves.
BBC Correspondent Will Grant joined one group searching the inhospitable desert of the northern state of Sonora.
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