Pinto is accused of being the instigator because he wanted to earn overtime.
The trio is alleged to have co-ordinated throwing lit cigarettes from their cars onto bone-dry vegetation in at least three different spots around Viña del Mar.
They hatched the plot at the height of the southern summer amid a record heat wave.
Scientists blamed the high temperatures on a combination of the El Niño weather effect and climate change that had seen drought conditions and forest fires from Argentina to Mexico.
After his arrest on Monday, Salazar was fired from his job at Senapred, the national disaster prevention and response agency.
Investigators also removed a computer and documents from his home.
Guillermo Gálvez, a senior detective, told journalists that Salazar’s main motivation was that he liked to “participate and be a hero, helping out once the emergencies were happening”.
Salazar had previously been disciplined, it was reported, for heading on his own to attend fires, in violation of strict firefighting protocol that required him to report for duty with colleagues.
He is due to appear in court on Tuesday.
