Like other observers, Reporters Without Borders is not entirely convinced by the Oaxaca state attorney-general’s announcement last week that a former public education employee, Lenin Osorio Ortega, has been arrested for the fatal shooting of US journalist Brad Will, an Indymedia cameraman, in the southern city of Oaxaca in October 2006.

Coming nearly six years after Will’s murder during a wave of unrest that was crushed violently by the Oaxaca state authorities, this new development has so far failed to dispel all the doubts and suspicion surrounding the case.

“While undertaking to respect the position of the Will family, which has yet to formally express its opinion, we have our reservations about the claims being made in connection with Osorio’s arrest,” Reporters Without Borders said.

“The past serious irregularities in this case, which was entrusted to the federal judicial authorities in 2007, have never been properly investigated and we have not forgotten that someone was wrongly accused and was held for more than a year before being released for lack of evidence.”

Will was killed while covering a large protest by a grass-roots opposition group called the Popular Assembly of the Peoples of Oaxaca (APPO) in Santa Lucia del Camino, on the outskirts of the city of Oaxaca, on 27 October 2006. He was fatally injured by shots that came from the direction of bodyguards employed by then Oaxaca state governor Ulises Ruiz Ortiz, a leading member of the Institutional Revolutionary Party (PRI).

The ensuing investigation was marred by tampering with ballistic and autopsy reports and the complete impunity enjoyed by individuals who were identified by many witness. Even more seriously, it led to APPO activist Juan Manuel Martínez Moreno’s arbitrary arrest as a suspect, an arrest condemned by the Will family. Martínez was finally released on 18 February 2010 and all charges against him were dropped.

The new suspect, Osorio, 39, a former employee of the Oaxaca Institute for Public Education (IEEPO), has a more plausible profile. The Will family’s Mexican lawyer, Miguel Angel de los Santos, told Reporters Without Borders: “Right from the outset, he was identified by witnesses as a member of a group of PRI supporters who were in Santa Lucia del Camino that day.”

But Oaxaca state attorney-general Manuel de Jesús de López’s insistence, when announcing Osorio’s arrest on 23 May, that the fatal shots were fired from some distance, is more likely to be disputed.

De Los Santos pointed out that the witnesses he took to the attorney-general’s office were sidelined and even threatened with prosecution. Calling for an investigation into former Governor Ruiz’s role, he said: “Will’s murder was not isolated. Two APPO members were also killed there.”

The news agency Proceso (which is linked to the newsweekly of the same name) has meanwhile reported that Osorio was arrested along with three other people on 9 March, not 23 May, as the attorney-general announced.

“All the aspects need to be checked,” Reporters Without Borders said. “We support the Will family lawyer’s initiatives. The investigation should explore all the leads, without trying to block examination of the most compromising aspects.

“Attempts to shed light on some of the other 83 murders of journalists - and 14 disappearances -in the past decade have been sabotaged or paralyzed by the complicity or, at best, incompetence of the investigators. The overwhelming majority of these cases are unfortunately still unpunished.”