The bodies were found after a ninth member of the Martinez family escaped Sunday's abduction near Casa Quemada, in the state of Chihuahua, and alerted the authorities, prosecutors said.
Eight people from the same family, including two teenagers, were kidnapped by masked gunmen and decapitated in northern Mexico, authorities said on Wednesday.
The bodies were found after a ninth member of the Martinez family escaped Sunday's abduction near Casa Quemada, in the state of Chihuahua, and alerted the authorities, prosecutors said.
The family was traveling in a vehicle when it was kidnapped by armed men wearing masks and dressed in military-like fatigues, the Chihuahua state prosecutor's office said.
The bodies of three men between the ages of 18 and 25 were found on a rural road on Wednesday.
A day earlier, authorities recovered five other bodies that had been dumped in different parts of Casa Quemada, including those of two 15-year-olds.
Some witnesses said the family had gone to the mountain region to cut wood while others claimed that the relatives cared for drug fields.
The mass murder took place in a region known as the Golden Triangle, which includes the states of Sinaloa, Chihuahua and Durango, where drug cartels grow marijuana and opium poppies.