The tortured body of a Mexican police reporter has been found on the side of a road in the northern state of Sonora on Friday. A day earlier he had been kidnapped by gunmen while waiting at a car wash.

Marco Antonio Avila Garcia's body was found inside a black plastic bag near the city of Empalme, about 68 miles south of Ciudad Obregon where he was abducted, said Sonora state prosecutors' spokesman Jose Larrinaga.

Larrinaga said police found a message signed by a cartel but would not reveal its content.

The 39-year-old reporter often wrote about organised crime for the sister newspapers Diario Sonora de la Tarde and El Regional of Ciudad Obregon, said Larrinaga.

Two weeks ago police found the mutilated bodies of three photojournalists inside plastic bags dumped in a canal in the Gulf coast state of Veracruz. Last week gunmen opened fire on the offices of the El Manana newspaper in the border city of Nuevo Laredo.

Avila had been snatched and forced into a pick-up truck on Thursday by three masked gunmen as he waited for a company car to be washed in Ciudad Obregon. The reporter was married and had three small children.

Mexico has become one of the world's most dangerous countries for journalists amid a government offensive against drug cartels and rivalry among crime gangs.

Mexico's National Commission on Human Rights has said 81 journalists were killed between 2000 and 2012, while another 14 have disappeared.

The commission said on Friday it had opened an investigation into the death of Rene Orta Salgado, a journalist who had quit working for El Sol de Cuernavaca newspaper in the resort city of Cuernavaca in January. Police found Orta's body inside his car's trunk last Sunday; he had apparently been strangled.

Separately, the Mexican army said it had detained eight suspected members of the Gulf cartel and seized drugs, guns and hand grenades during investigations into the 13 May discovery of 49 mutilated bodies on a highway in northern Mexico.

Mexico's defense department said the suspects were caught on Thursday.

But the department has not said whether the eight suspects were directly involved in those killings.
The department said ib Friday that a total of 44 people had been detained and 140 guns and about four tons of marijuana seized during the investigations.

Authorities had previously suggested the rival Zetas cartel was responsible for the killings.