Mexican police say 55 bodies have been recovered from an abandoned mine that appears to have been used as a mass grave by drugs gangs.
Human remains were first discovered in the silver mine near Taxco in Guerrero state at the end of May.
The bodies appeared to have been thrown down a 200m (650ft) ventilation shaft over a period of time, police said.
Earlier reports that 77 bodies had been recovered were mistaken, officials said.
Only six have so far been identified - one was the director of a local prison.
Guerrero state is a focal point for drug-related violence that has claimed more than 22,000 lives in Mexico since 2006.
Police are now checking other mineshafts in the area to see if bodies have also been dumped there.
Police and civil defence workers used breathing equipment to descend deep underground to recover the bodies.
They are taking photos and DNA samples in the hope of identifying the dead.
Some corpses have tattoos associated with the drugs gangs, police said.
Local morgues have been overwhelmed by the number of bodies.
While most of the drug-related violence over the past four years has been concentrated in northern Mexico along the border with the US, other regions have not been immune.
Guerrero, in the south and with a Pacific coastline, has also seen bloody turf wars for control of drug smuggling routes.