Investigators have narrowed down where the Black Forest Fire broke out, but El Paso County Sheriff Terry Maketa (mah-KEE'-tah) says they might never know for sure how Colorado's most destructive fire started.

Maketa did not reveal the location during a briefing Tuesday on his office's "after-action" report. He says smoking, a campfire and a train have all been ruled out as fire starters.

Once the U.S. Forest Service finalizes its report on the fire, Maketa says his office's findings will be turned over to prosecutors to determine if criminal charges are warranted.

Investigators previously said the fire was human-caused, but Maketa has said there is no evidence it was intentionally set.

The Black Forest Fire started a year ago this week. It destroyed nearly 500 houses and killed two people north of Colorado Springs.