The two journalists and a human rights specialist behind "Permission to Kill" investigated more than 1,800 killings under three presidents since 2006, including outgoing leftist Andres Manuel Lopez Obrador.

The aim was to show the "systemic" nature of murders allegedly involving members of the security forces, said co-author Daniel Moreno, director of the news site Animal Politico.

"It's not a collection of anecdotes," he told AFP.

"There is a constant in these three governments of attacking the civilian population and letting the attackers go unpunished," Moreno said.

Investigators identified 494 such alleged crimes -- mainly killings and forced disappearances -- during the 2006-2012 presidency of Felipe Calderon, 808 under his successor Enrique Pena Nieto (2012-2018), and 489 during Lopez Obrador's first four years in office.

But that is not believed to be all the cases, they say.

The defense ministry, which oversees the military, did not respond to a request by AFP for comment on the allegations against it.

More than 450,000 Mexicans have been killed and tens of thousands have disappeared since Calderon deployed the military against drug cartels in 2006, according to official figures.

Under a policy that he calls "hugs not bullets," Lopez Obrador pledged to prioritize addressing the root causes of crime, such as poverty and inequality, over going to war with the cartels.

During his presidency, "there was less use of force and more respect for life," Lopez Obrador said Sunday in his last state of the nation report before he is replaced by his ally Claudia Sheinbaum on October 1.

- Parallels with Colombia -

Co-author Paris Martinez sees similarities with the more than 6,000 murders and disappearances investigators say were committed by the Colombian army from 2002 to 2008 to try to make its fight against guerrilla groups appear more effective.

The book, which is also the work of human rights expert Jacobo Dayan, argues that there has been a repeated failure to investigate or punish those responsible, some of whom are still active or have been promoted.

"They arrested the people who fired the shots, not those who designed the strategy," Moreno said.

Of the more than 1,800 cases examined, only 133 resulted in convictions, according to the authors.

Rights group Amnesty International said in a report released in April that Mexican military forces "continued to use unnecessary and excessive force and carry out extrajudicial executions" last year.

"Impunity persisted for these crimes and human rights violations," it said, noting the case of five men allegedly killed by soldiers in February 2023 in the northern border city of Nuevo Laredo.

The book's authors will hand over their work to the local office of The Hague-based International Criminal Court, which investigates war crimes and crimes against humanity, Martinez said.