Lopez Bello, 28, was found dead July 17 in Trinidad de Viguera, having been beaten and shot. He was a reporter for La Imparcial (The Impartial) and had recently run a series of stories about drug sales in the state, a statement from the Committee to Protect Journalists said.
The committee, as well as the U.N. Educational, Scientific and Cultural Organization called for a full investigation of the slaying.
"I condemn the murder of Alberto Lopez Bello," said the Director-General of UNESCO, Irina Bokova.
"Crime reporters in Mexico work at enormous risk, constantly facing threats, intimidation and attacks that are virtually never punished," Carlos Lauria, CPJ's senior program coordinator for the Americas, said. "The cycle of impunity in anti-press crimes has had a devastating effect on the public's right to information, especially on matters of crime and corruption. The government can begin to break this terrible cycle by fully investigating this crime."
Oaxaca Gov. Gabino Cue Monteagudo said the state will fully investigate Bello's death, adding he plans to ask the federal attorney general's special prosecutor for crimes against journalists to join the inquiry, the CPJ statement said.
Bello's body was found next to that of Arturo Alejandro Franco, an undercover police informant.
Bello was the third journalist to be slain in Mexico this year.