Wess Roley — the man accused of setting a brush fire and launching a sniper-style ambush on firefighters in Idaho this weekend — once had dreams of becoming a firefighter himself, according to investigators.

Kootenai County Sheriff Bob Norris revealed the 20-year-old’s ambitions at the Monday press conference — but says it’s unclear if that had anything to do with Sunday’s deadly incident.

Officials also revealed Roley died from what appears to be a self-inflicted shotgun wound. So far, no manifesto, no confirmed suicide note … and no clear motive.

Authorities say Roley’s family is aware of the investigation and is still processing the tragedy.

As TMZ told you earlier, Roley’s remains were sent to the Spokane County Medical Examiner’s Office in Washington — which handles cases from neighboring Kootenai County across the state line.

It all followed a wild shootout — Roley allegedly lured firefighters to the blaze on Canfield Mountain near Coeur d’Alene before ambushing them. His body was later found in the woods after authorities traced his cell signal. Norris said Roley did “contact” the firefighters when they arrived at the scene … “there was a discussion” before he opened fire.

A third firefighter was also hit and remains in critical condition as of now.