A demonstrator shows a picture of murdered Mexican journalist Javier Valdez during a protest by journalists in Mexico City on May 16. (Pedro Pardo/Agence France-Presse via Getty Images)

WHEN ONE of his colleagues at Mexico City’s daily newspaper was gunned down in March, Javier Valdez issued a passionate statement about the importance of the work of journalists who cover the network of organized crime, drug trafficking and corruption that plagues Mexico.“Let them kill us all, if that is the death sentence for reporting this hell,” he tweeted. “No to silence.”

The words proved horribly prophetic when Mr. Valdez last week became the latest casualty of the drug-fueled violence that has claimed tens of thousands of Mexican lives over the past decade. The life and death of this courageous reporter should serve as inspiration and prod to the Mexican government to undertake reforms needed to end the impunity that allows the country’s lawlessness to flourish.

Mr. Valdez, 50, was shot and killed at midday May 15 on a busy street in the northwest state of Sinaloa. Authorities said unidentified attackers fired 12 shots at his car. Sinaloa is a drug trafficking destination perhaps best known as the home of Mexican drug lord Joaquín “El Chapo” Guzmán; Mr. Valdez, a correspondent for La Jornada, co-founded a regional weekly newspaper there in 2003 because of his belief in the need for honest reporting of the crime and corruption that victimize Mexicans — despite the risks.

He is the sixth journalist to be killed in Mexico this year and one of more than 100 journalists who have been murdered since 2000. Eleven days before Mr. Valdez’s death, a delegation from the Committee to Protect Journalists met with President Enrique Peña Nieto to present its newly released report “No Excuse: Mexico Must Break Cycle of Impunity in Journalists’ Murders.” Among the recommendations were better protections for at-risk journalists, timely investigation of threats and training prosecutors in how to pursue crimes against freedom of expression.

It’s good that Mr. Peña Nieto immediately and strongly condemned Mr. Valdez’s murder, but that is clearly not enough. Recommendations of the CPJ report should be embraced, and the chronic failure of the judicial system in investigating and prosecuting crimes must be addressed. A good place to start is making a priority of finding those who shot Mr. Valdez and those who ordered it.