SANTIAGO, Chile — A judge in Chile on Thursday convicted 11 former members of the country’s army for the 1986 murder of Rodrigo Rojas, a United States-based Chilean photographer who was burned alive during protests against Gen. Augusto Pinochet, the dictator who ruled Chile from 1973 to 1990.

In a 546-page ruling, Judge Mario Carroza sentenced three ex-officers, Julio Castañer, Iván Figueroa and Nelson Medina, to 10 years in prison. Eight other soldiers were given suspended sentences and two were acquitted.

Mr. Rojas’s mother, Verónica De Negri, a government critic, went into exile in the United States in 1977. Her son joined her and attended Woodrow Wilson High School in Washington, where he practiced his passion for photography.

On July 2, 1986, a few months after Mr. Rojas returned to Chile at age 19, he and a university student, Carmen Gloria Quintana, 18, were detained by a military unit commanded by Lt. Pedro Fernández in a working-class neighborhood of Santiago, the capital, during a tense day of street protests. Mr. Rojas had planned to photograph the day’s events.