The cause of the Butts Fire in northern Napa County, which grew to over 4000 acres in July 2014 before being contained, remains under investigation two years later, but the remains of two men who were caught in the quickly moving blaze may finally provide a clue. As the Santa Rosa Press Democrat reports, bones discovered on a remote hillside near Butts Canyon last spring have just been identified as the remains of brothers Mario Avendano, 31, and Florentino Avendano, 45, both missing since July 2014. Both men lived in Santa Rosa, and their family waited six months to file a missing persons report on them for reasons that aren't totally clear — though it's possible it's because they knew the brothers were up to something illegal.

Illegal marijuana grows are common the Butts Canyon vicinity, which runs between Napa and Lake Counties, with 42,000 pot plants seized by authorities there just this year, according to the paper. And, as firefighters arrived to battle the Butts Fire on July 1, 2014, they reported seeing two Hispanic men running from the area, who were likely the Avedano brothers. Firefighters told investigators that they tried to contact the men, but weren't able to locate them later.

Family members were just informed this week, and they've apparently given no reason for why the brothers were in the Butts Canyon area at the time — but the brothers were likely living or camping in the immediate vicinity of the grow, and their family had not seen them since a month before the fire, in June 2014.

There was no evidence of foul play on the two men's remains, however investigators only found several bones belonging to two different people and one skull — indicating possible animal predation? The brothers' cause of death remains unknown.

As the Napa Valley Register reports, the bones were spotted by concrete workers in the area in March of this year. They reported spotting what looked like a skull, and did not report it until they spotted it a second time over several days.

Relatedly, an illegal marijuana grow has been pegged as the possible cause of the Loma Fire, still burning in Santa Clara and Santa Cruz Counties, and marijuana growers were caught in the middle of the Soberanes Fire earlier this summer, and required rescue. That latter fire, caused by an illegal campfire north of Big Sur, just reached 96 percent containment today, after burning over 130,000 acres over two months.