A suspected member of the Zetas drug cartel led Mexican authorities to mass graves at two ranches in the Gulf coast state of Veracruz where marines unearthed 15 bodies by Wednesday.
The navy said its personnel detained Francisco Alvarado Martagon on Tuesday when he tried to drive a vehicle without license plates past a military checkpoint near the city of Acayucan.
Once in custody, Alvarado Martagon confessed to being a head lookout for the Zetas, the navy said.
Under questioning, the man mentioned two sites at local ranches that the Zetas allegedly used to dispose of bodies, including rivals or members of their own gang who had been executed, it said.
The navy announced Wednesday morning that marines inspected the sites and found the buried, decomposed remains of 10 people but were still searching. The security force increased the number of bodies to 15 later Wednesday.
Veracruz has been the scene of bloody battles between the Zetas and the Sinaloa drug cartel.
Mexican authorities have found hundreds of bodies dumped by drug gangs in mass graves in recent years, mainly in the northern states of Durango and Tamaulipas.