MAGADI, India — M. R. Gundappa, 60, died the way most Indians do: with no doctor present, no monitors beeping by his side and no written record. The only person present was his wife, Sushilamma, 48, who spent the day of his death trying to get him admitted to a government hospital where he could be treated for abdominal pain.

On a recent afternoon, Sushilamma spent an hour trying to retrieve her memories of the fateful day in 2013 for an official from the Office of the Registrar General of India, who sifted through her story for clues to what had caused her husband’s death.

Nearly 70 percent of deaths in India, five million in all each year, take place in the absence of medical supervision, according to the office, which is responsible for registering births and deaths.

To fill this gap, a new survey, the Million Death Study, is trying to turn the clock back on a million premature deaths that took place between 2001 and 2014, sifting through evidence provided by families and caregivers. By assigning causes to these deaths, based on the accounts of witnesses, the study hopes to identify the major causes of premature death in India.