Police found a decapitated body wrapped in a blanket and a human head stuffed in a plastic bag outside this industrial city, in the latest in a series of beheadings apparently linked to drug traffickers.

Alongside the body, which was identified on Monday as 17-year-old Julio de Leon of Nuevo Laredo, were two notes addressed to reputed drug lord Joaquin "El Chapo" Guzman of the Sinaloa cartel, said Nuevo Leon state investigator Marcelo Garza.

One note read: "These are the ones who are killing in Laredo and also in Guadalajara under the orders of Efrain, El Beto y El Pipo. They are El Chapo's people."

The second note accused the government of protecting Guzman and said the killings would stop if police arrested Arturo Beltran and Edgar "La Barbie" Diaz Villarreal, suspected Sinaloa cartel gangsters.

Authorities say the Sinaloa cartel is fighting a bloody turf war with the rival Gulf cartel causing execution-style killings, beheadings and grenade attacks across Mexico. A hot spot has been Nuevo Laredo, over the border from Laredo Texas.

Garza said they were investigating links between Monday's grisly discovery and an attack on federal investigator Veronica Palacios Espinoza, who was ambushed and seriously wounded while driving through a residential neighborhood on Sunday.

Witnesses told police that at least 15 gunmen wearing ski masks and traveling in three cars fired more than 100 rounds at Palacios' sports utility vehicle. An unidentified woman riding with her was killed, while brothers Efrain, Tomas and Roberto Lopez de la Cruz of Nuevo Laredo were wounded.

Decapitated teenager De Leon was a cousin of the Lopez de la Cruz brothers, Garza said.

"We're trying to determine a possible link (between the two incidents) since the names of the two people we're questioning, Efrain and Roberto, coincide with those written in the messages," Garza said.

Late Monday, investigators found another body of a man whose hands were tied with barbed wire about a mile from where police located de Leon's dismembered body.

In the last few months, police have found decapitated bodies in the central state of Michoacan, in the border state of Baja California and in the Pacific resort town of Acapulco.