El Niño Hollywood was a scrappy preteen, dirt-poor and wide-eyed, when he met Chepe Furia. The 26-year-old, hardened by the Mara Salvatrucha gang on the streets of Los Angeles, had recently returned to El Salvador to build his child army. It was 1994. Furia flashed his shiny truck and brand-name clothes to reel in El Niño and two dozen of his adolescent friends. In abandoned houses in the province of Ahuachapán, he told stories of great battles against the Barrio 18 gang, and forced the boys to beat the hell out of each other. He showed them his weapons: one 9mm and two .22-caliber pistols. That was it—they were in.

Furia named his new posse the “Hollywood Locos” and declared war on the rival gang. El Niño was 15 years old when he grabbed one of the pistols and, to impress Furia, shot a Barrio 18 member, slitting his throat for good measure. He and his fellow apprentice assassins would drink and smoke pot at Furia’s two-story house, which served as a lookout for police. Some of the boys would arrive still wearing their school uniforms.

A HISTORY OF VIOLENCE: LIVING AND DYING IN CENTRAL AMERICA by Óscar Martínez Verso, 288 pp., $24.95

Nearly two decades later, in 2012, when Óscar Martínez started reporting about El Niño for El Faro, a San Salvador–based online publication dedicated to investigative journalism, the gangster was living in a shack with his teenage wife, smoking crack to pass the time, cocking the triggers of two pistols at the sound of any stir. Whole swaths of El Salvador belonged to the gangs, making the country one of the most murderous in the world. El Niño himself had 56 kills: “About six women and the rest men. I’m including faggots as men, ’cause I’ve killed two faggots,” he bragged to Martínez.

But fortune had caught up to El Niño. He was 29—over the hill in gangster years. His murders and several stints as a protected witness had flooded the valley with his enemies, and he knew his time was running out. Martínez, aware his reportorial project had an expiration date, started visiting El Niño once a month. El Niño welcomed the visits—he had nothing to lose—and awaited his own death.

The story of El Niño Hollywood snakes through Martínez’s new book, A History of Violence: Living and Dying in Central America, a compilation of 14 articles Martínez wrote between 2011 and 2015 for the crime investigations desk of El Faro, translated by John B. Washington and Daniela Maria Ugaz. It’s the story of how a war-torn region became a gang-torn one and how the governments of El Salvador, Guatemala, and Honduras have categorically failed to protect their young men and women from becoming victims of the gangs, and in many cases, from becoming the victimizers.