The list includes four of the five journalists killed in Mexico so far this year, as well as one killed last year and an editor badly wounded in a gun attack last month.
The reward -- a maximum of 1.5 million pesos for each case -- "will be paid in proportion to the accuracy, usefulness, effectiveness and timeliness of the information provided in locating the attackers," the attorney general's office said in a statement.
Mexican journalists often pay a heavy price for covering the bloody wars between the country's rival drug cartels and the army.
More than 100 reporters have been killed here since 2000, and more than 20 are missing.
Ninety percent of the cases have never been solved. Human rights groups accuse the authorities of indifference -- and even involvement in some cases.
The reward offer includes the high-profile case of Javier Valdez, a noted crime reporter gunned down in broad daylight in the violent state of Sinaloa on May 15.
It also includes the cases of colleagues Cecilio Pineda, Miroslava Breach, and Maximino Rodriguez, all killed in 2017, and Sonia Cordoba, deputy editor of the weekly newspaper El Costeno, who was shot and wounded on May 15.
It does not include their colleague Ricardo Monlui, who was killed in March and whose case remains unsolved.
The attorney general's office did not explain how it decided which cases to include. Officials did not immediately respond to requests for comment.
Despite international condemnation triggered by Valdez's killing, violence against journalists has continued in the month since his death.
Reporter Salvador Adame remains missing after being kidnapped on May 18 by gunmen in the western state of Michoacan.
Another journalist, Andres Crespo, was kidnapped and beaten in the eastern state of Veracruz earlier this month before being released.
According to watchdog group Reporters Without Borders, Mexico is the deadliest country in the world for journalists after Syria and Afghanistan.
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