The decapitated bodies of about 50 people were found dumped on the side of a major Mexican highway linking Monterrey to the border city of Nuevo Laredo.
Authorities believe it is yet another example of the vicious drug war that has killed some 50,000 people in Mexico.
The bodies were accompanied by a spray-painted message, indicating that the killings were done by the Zeta drug cartel, who have remained embroiled in a violent struggle against Mexico's oldest and largest trafficking cartel, the Sinaloa group.
Ioan Grillo, Reuters reporter and author of the book "Narco: Inside Mexico's Criminal Insurgency," joins the show from Monterrey to discuss Mexico's drug wars.
Ioan Grillo is a reporter for Reuters and author of the book "Narco: Inside Mexico's Criminal Insurgency."