Updated

Mexican police on Thursday were investigating the shooting death of a man whose dismembered body was found stuffed into four plastic bags dumped along a highway leading to the Pacific resort of Zihuatanejo.

Authorities said they recovered a note written on a piece of cardboard among the body parts, according to the attorney general's office in Guerrero, where Zihuatanejo is located. It was signed by "The Shadow," and appeared to threaten a group of men linked to drug smuggling.

However, Eduardo Murueta, the state attorney general, refused to confirm those details.

A police cruiser patrolling near the town of El Chico found the remains late Wednesday.

One black plastic bag contained the unidentified victim's head, covered by a gray T-shirt and wrapped in plastic tape. Another held the man's legs — his ankles bound by tape — and a third contained his arms and part of his torso, Murueta said. Additional bags held other remains, tape and bandages, fresh grass clippings and an empty beer can.

Forensic teams recovered dozens of machine gun rounds nearby and said the victim had likely been shot to death.

The note found with the body parts began "There you are," and threatened three men who it said were being protected by the Federal Agency of Investigation — the Mexican equivalent of the FBI — and other groups, according to investigators from Murueta's office. One of those listed was Edgar "Barbie" Diaz Villarreal, a reputed drug smuggler with links to the Sinaloa cartel.

"I will find you," the note ended. On the other side was a large letter "Z."

In Acapulco, another Pacific resort 120 miles east of Zihuatanejo, authorities last month found the head of a former Mexican soldier, Hugo Carpio Garcia, near the entrance to city hall with a note signed by "Z." Authorities said it refers to "Las Zetas," a group of former elite Mexican soldiers who are now believed to work for the Gulf drug cartel.

Acapulco has been shaken this year by high-profile gun slayings as well as several grenade attacks on police stations. Six victims had their heads severed and dumped around the city in decapitations authorities said were carried out by drug smugglers looking to send authorities a message.

Anti-narcotics investigators say the rural area around Zihuatanejo is also a hotbed for drug trafficking.

On Thursday, neighbors near El Chico told investigators they heard automatic gunfire shortly before the body was discovered, just off a highway linking the resort and the port city of Lazaro Cardenas.

La Union is 30 miles northwest of Zihuatanejo.