Police in Northwest Pakistan found the body of a health worker in a field near the city of Peshawar.
Salma Ghani was taken by force from her residence on Sunday by a group of unidentified armed men.
According to the authorities, Ghani was tortured and shot several times.
Her family believes that she was kidnapped because of her work in a local polio immunization program.
It is believed that in the past 15 months that over forty people of vaccination teams have been killed.
Islamist militants oppose the vaccination programs because they believe that they are part of a plan of the West to sterilize Muslim women and also to cover up espionage.