By Caroline Brothers MEXICO CITY, July 16 (Reuter) A crusading antinarcotics journalist was gunned down in a remote town on the MexicoU.S. border after receiving death threats from a lieutenant of dead drug lord Amado Carrillo Fuentes, witnesses said on Wednesday. Benjamin Flores Gonzalez, 29, died in a hail of bullets late on Tuesday after unknown gunmen opened fire with an AK47 rifle and finished him off executionstyle with a .22 calibre pistol, witnesses and colleagues said. Bullets ricocheted off the walls of nearby buildings and bystanders said they found about 30 cartridges on the ground after the attack. The footpath was covered in blood. The shooting took place outside the offices of La Prensa, the newspaper Flores directed in the border town of San Luis Rio Colorado, on the border with Arizona in Mexico's Sonora state. Colleagues said they feared the murder of Flores, who also faced five lawsuits for defamation because of his investigative stories, was related to his antidrug reporting. ``We and the justice officials have established as a starting point for investigation the possibility that narcotraffickers were involved that is the firmest hypothesis,'' Jesus Barraza, La Prensa's news editor, told Reuters in a telephone interview. ``The police are following some important leads.'' State Attorney General Rolando Tavares Ibarra told reporters the death looked like ``a settling of accounts by drug lords.'' An international body set up for the defence of journalists sent a letter to Sonora state Governor Manlio Fabio Beltrones on Wednesday asking him to investigate the death. ``Because of Flores' aggressive coverage of the drug trade...we fear that this brutal murder was related to his activities as a journalist,'' the letter from the Committee to Protect Journalists said. ``We respectfully suggest that the authorities investigate whether there is any connection between the criminal complaints and the murder.'' Flores, who founded La Prensa five years ago, wrote a hardhitting column called ``No Confirmada'' (Unconfirmed) where he criticised politicians, including the governor's brother Orestes Beltrones, and denounced the drug barons, including Hector Palma, the nowjailed head of the Sinaloa cartel. In May this year he reported the theft of half a tonne of cocaine from Federal Judicial Police Headquarters in San Luis Rio Colorado after it was confiscated by local authorites. Police said he spent several months in jail some years ago after losing a court case against the Sonora government. Barraza said Flores had received a death threat two to three months ago from a lieutenant of dead cocaine baron Amado Carrillo Fuentes. Carrillo died two weeks ago after undergoing extensive plastic surgery to change his appearance in a small Mexico City hospital. He headed the socalled Juarez Cartel based in neighbouring Chihuahua state.