(CNN) -- Three years after the killing of Mexican journalist Armando Rodriguez, his colleagues said they are more determined than ever to write about the nation's drug cartels despite the risks.
"Those who ordered the killing of Armando were wrong because those who are left are more seasoned and we are working," said Luz del Carmen Sosa, a reporter for El Diario de Juarez newspaper who took over Rodriguez's crime beat after his death. "Those who believed we were going to take step back, they were wrong."
On November 13, 2008, Rodriguez -- called "El Choco" by his colleagues because of his chocolate skin tone -- was about to take his two young daughters to school when a man approached the garage of his house and fired 11 shots into his chest. His daughters, one of whom witnessed the attack, have not spoken publicly since the incident and did not attend a memorial event for their father on Sunday. Rodriguez's wife declined an interview request from CNN.
His colleagues believe he was targeted because of his coverage of drug cartels in the border town of Ciudad Juarez.
Before his death, Rodriguez was among the first journalists to write at length about the violent shift in the city. He was a high-profile reporter for the most-read paper in the city, covering a dangerous beat. It was a job his friends believe cost him his life.
Local reporters now look at the killing as the first of many targeting journalists for their work.
Since 2000, 74 journalists have been killed in Mexico -- 14 since 2010.
On the third anniversary of his death, his newsroom colleagues gathered Sunday to pay tribute and "remember Choco ... friend, journalist, family man and a great man," the paper's editorial assistant Pedro Torres said at the public event.
His colleagues criticized the investigation into his unsolved killing, saying it is an example of the hundreds of unsolved murders throughout the city -- widely considered to be one of the most violent in the world.
Sandra Rodriguez Nieto, an El Diario reporter, said she believes that someone is "hiding those responsible" for Rodriguez's death.
It's a charge prosecutors with the Chihuahua State Attorney General's Office have denied. Early in the investigation they announced the detention of a suspect in the shooting, but never released details about who they held. The lack of information led to speculation among El Diario's newspaper staff that there was a cover up.
Making matters more complicated were attacks on the investigators working on the case.
In July 2009, a convoy carrying José Ibarra Limón, the first federal prosecutor designated to Rodriguez's case, was riddled with bullets by unknown assailants. The following August, Pasillas Paul Fong, the secretary of the Seventh Agency who would inherit the case, was executed. Days later, a third investigator took the case, only to flee Juarez soon afterward.
"This is a situation that hurts, an unacceptable situation," Torres said.
Of the five publications in Juarez, El Diario de Juarez is the most popular paper in terms of circulation and has made a reputation for aggressively covering drug violence.
In September 2010, two of the paper's photographers were attacked -- one was killed. A clear motive was never established, but investigators at the time did note the car carrying the two young journalists was registered to the son of the inspector of the State Human Rights Commission, Gustavo de la Rosa Hickerson. Some believe the journalists were not the intended targets of the attack.
On the same day friends and family buried the slain photographer, the newspaper published an open letter to the drug cartels operating in Juarez. The letter, written by the editorial staff, pleaded for an end to violence against journalists.
No newspaper in Juarez had ever published an editorial directly addressed to the cartels; and no other paper has done so since.
"You are, at present, the de facto authorities in this city," the letter said, "because the legal institutions have not been able to keep our colleagues from dying."
In the wake of Rodriguez's death, del Carmen Sosa said she has no fear and was ready to take full responsibility for her work, even if it means death. She said she operates under the same mantra as her predecessor.
"Unlike Armando Luis Carlos (Rodriquez), I'm alive," del Carmen Sosa said. "I try to be responsible with my journalism and I have no fear."
In 2010, she was presented with an award for her courageous reporting.
"I can only thank God every day ... because we need justice not only for Armando but for all the homicides in this city," she said.