The bound and burned bodies of eight men were found in the central Mexico state of Queretaro, prosecutors said Saturday.
The still-unidentified bodies were discovered in the back of two burned-out trucks on a rural road late Friday, state and federal prosecutors said in a statement.
The victims' hands were tied behind their backs with wire, and they were apparently killed elsewhere.
Also Saturday, in the northern state of Chihuahua, officials reported that gunmen killed four police officers in a series of attacks on patrol cars in the border city of Ciudad Juarez on Friday.
State police spokesman Fidel Banuelos said the first attack killed two brothers who were patrolling together but worked for different agencies.
Police and prosecutors said two more officers were wounded in two other attacks.
There was no immediate information on possible motives. Nearly 2,500 people have died in drug-related violence this year in the city across from El Paso, Texas.
And federal authorities announced Saturday that a suspect in the high-profile 2005 kidnapping of businessman Hugo Alberto Wallace, whose mother later went on to become an anti-crime crusader, has been taken into custody in Mexico.
The federal Attorney General's Office said Salomon Tagle was expelled from the Dominican Republic flown to Mexico, where he was taken into custody on kidnapping charges.
Several other suspects have been arrested in part as a result of investigations carried out by Wallace's mother, Maria Isabel Miranda. Frustrated with investigators' lack of progress in her son's case, Miranda launched her own probe and a public campaign to press for justice.
Her son was presumably killed by his kidnappers, but his body has never been found.