Thirteen bullet-riddled bodies were found along a dirt road Thursday in Mexico's Sinaloa state, home to the powerful cartel of the same name.
The victims, whose hands were bound, were found near the town of Coyotitlan along with 80 bullet shells, federal police agent Juan de Dios Beltran said.
Mexico has been suffering from escalating drug violence amid a national crackdown on traffickers. Homicides have grown increasingly gruesome, with piles of bodies dumped in public, sometimes beheaded.
More than 5,000 claimed by violence
El Universal newspaper reported Wednesday that, according to its count, more than 5,000 people have died in drug-related violence this year. The government only sporadically releases nationwide homicide figures.
President Felipe Calderon has deployed more than 20,000 soldiers across the country to combat drug traffickers. At the same time, the government is struggling to rid its security forces of corrupt officers in the pay of cartels.
On Thursday, a judge ordered a high-ranking federal police officer to stand trial for allegedly leaking information about police checkpoints and other operations to the Zetas, a group of hit men for the Gulf Cartel.
Javier Herrera, a former federal police director in several Mexican states, has denied the allegations, claiming he is being persecuted for complaining about mismanagement in the federal police.
He is one of several officers arrested in "Operation Clean House," an investigation into corruption at the federal police. The highest-ranking officer detained was Noe Ramirez, Mexico's former drug czar.