Law enforcement officers in Mexico have found 166 human skulls in burial pits in the Gulf coast state of Veracruz.
Veracruz state prosecutor Jorge Winckler said the bodies had been in the mass graves, one of the biggest found in Mexico, for at least two years.
Investigators also found 144 identity cards in the surrounding field, which had 32 separate burial pits. Due to security concerns, Winckler would not reveal the location of the graves.
Winckler said other personal items and clothing were also found on the site but that the investigators would focus on the skulls to determine the exact number of victims.
Investigators have been using drones, probes and ground-penetrating radar for nearly a month after being tipped off about "hundreds of bodies" buried there.
Drug-related violence has been soaring in Mexico since 2006, and Veracruz has been at the heart of the bloodshed as the scene of turf battles between the Zetas and Jalisco drug cartels.
In 2017, Winckler had announced the discovery of more than 250 skulls in unmarked burial pits outside the state capital.