Mexican authorities now say the remains of 51 people have been found buried in mass graves near the northern city of Monterrey.
Investigators said Saturday that the bodies of 48 men and three women were uncovered following an anonymous tip. Authorities were using refrigerated trucks to hold the bodies, many of which had tattoos.
Officials also say forensic testing will have to be used to identify the remains.
Officials suspect the site where the bodies were found may have been used by drug cartels in the country's long-running drug war.
Monterrey is the capital of the state of Nuevo Leon, which has experienced a recent increase in drug-related violence.
In a separate case last May, authorities in southern Mexico found 55 bodies in an abandoned silver mine. Officials say the mine, near the tourist town of Taxco, became a dumping ground for victims of the country's lethal drug war.
At least 23,000 people have been killed in drug-related violence since President Felipe Calderon began cracking down on the cartels in 2006. Thousands of troops have been deployed across Mexico to fight the drug gangs.
Some information for this report was provided by AP and Reuters.