The fireline moves towards the city at the Monument Fire on June 15, 2011 near Sierra Vista, Ariz. Photo by Dean Knuth/Arizona Daily Star

The Monument Fire raging south of Sierra Vista is the latest major fire in Southern Arizona that was started in rugged, mountainous corridors frequently used by cross-border people and drug smugglers. The Horseshoe 2 Fire northeast of Douglas and the Murphy Complex Fire northwest of Nogales also originated in popular smuggling corridors.

As I wrote about in this Sunday article — "Many in S. Ariz. fire zone blame border crossers" — there has been widespread speculation that those two fires may have been caused by illegal border crossers or smugglers even though fire investigators have said only they believe they were human caused.

The same speculation is now occurring among residents in the Nicksville/Hereford/Sierra Vista area who live near where the Monument Fire burns.

The fire started on Sunday near the U.S.-Mexico border in the Huachuca Mountains, according to this InciWeb fire information page. The Huachuca Mountains are frequently trafficked by drug smugglers and guides of illegal immigrants, visible from the many trails and tons of trash left behind up there. 

That doesn't mean it was set by one of them, of course, but it certainly gives the question legitimacy.

Officially, fire officials haven't even announced yet if they believe the fire was caued by lightning or people, though one would assume it's going to be labled a human caused fire based on the lack of lightning in the area.

At a community meeting held Wednesday evening in Sierra Vista, several residents asked about the cause of the fire and the possibility that it may have been set by illegal immigrants or drug smugglers. One resident pointed out that the Coronado National Forest had been closed to visitors since June 9 at noon — three full days before the fire started.

Fire officials didn't really address the question, citing the ongoing investigation. They declined to address the topic with me, too, when I inquired about it last week for the Sunday story.

It's understandable, of course, for several reasons. First, the fires are still under investigation. Officials are not going to speculate about something without knowing for sure. Secondly, fire officials know the issue of illegal immigration is an extremely volatile issue and take great precaution to avoid creating a stir with their comments.

But when pressed at community meetings and press conference, officials have at least acknowledged that it's a possibility. At a press conference on June 6, Coronado National Forest supervisor Jim Upchurch said causes of fires include ricocheting bullets, campfires, welding equipment and possibly ignition by smugglers or illegal immigrants.

And at the meeting last night in Sierra Vista, Kym Hall, Coronado National Memorial superintendent, said in response to a question about it that it's a possibility they would like answered as well. She said investigators were on their way from Tucson, but she cautioned that it's a difficult question to answer.

"I can't tell you to be honest if we are going to have an answer," Hall said.

As I discovered in my research for the Sunday story, fire investigators don't focus on the nationality or immigration status of who started fires. First and foremost, they try to determine if a fire was caused by lightning or people. With fires presumed to be started by people, the focus is on finding a specific cause such as cigarettes, campfires or sparks from electrical equipment — not on determining where the people were from.

And from what I can tell, there's been little (or no) research done to shed more light on the topic. I asked a fire ecologist at Northern Arizona University's Forestry School if anyone there had researched the frequency of fires caused by smugglers or illegal border crossers. She said no, and that she was unaware of any plans to research the topic, either.

After this fire season, though, the question may become too pertinent not to address. We've now had three fires started in frequently used smuggling corridors that have burned 261,500 acres to date.