An empty sign and crumbled bricks are all that remain of Ricardo's Mexican Restaurant, one of a few business claimed by the Monument Fire, along Highway 92 in Sierra Vista, Ariz.

Photo by Greg Bryan, Arizona Daily Star

Illegal border crossers have been responsible for five of 31 fires that investigators have solved from 2002-2011 in the Southwest Border area of the Coronado National Forest.

I found this intriguing statistic during research for my story in last Sunday’s Arizona Daily Star —  Bill exempts Border Patrol from enviro laws in wide area.

It comes from written testimony submitted by Jim Peña of the National Forest Service to the Subcommittee on National Parks, Forests and Public Lands for a July 8 hearing on H.R. 1505. In addressing a host of border-related issues his agency deals with it, Peña addressed the prevailing questions about fires caused in smuggling corridors.

He said there have been 457 fires that have been determined to be human-caused in the Southwest Border area of the Coronado National Forest from 2002-2011. Of those fires, investigators have been able to determine who started 31 of them.

Of the 31, five were determined to have been caused by illegal border crossers, Pena wrote.

During this summer’s fire season, three major fires were started in rugged, mountainous corridors frequently used by people and drug smugglers. That led to speculation that some, or all, of these fires may have been caused by illegal immigrants or smugglers.

Sen. John McCain and Cochise County Sheriff Larry Dever were among those who weighed in support of this theory. Other law enforcement officials acknowledged that, at the very least, it was a legitimate question.

But as I reported in mid-June, federal officials declined to address the speculation about this summer’s fires, citing ongoing investigations. And with past fires, fire officials said annual fire reports from government agencies focus solely on how many fires were caused by people versus lightning.  And with fires presumed to be started by people, the focus is on finding a specific cause - not on determining where the people were from.

So with this dearth of information, Peña’s testimony is enlightening, even if it is not totally comprehensive. For instance, the Coronado National Forest does not cover all the areas in Southern Arizona where fires have occurred.

Two percentages jump out to me in these numbers:

• 7 percent — that’s how many of the 457 human-caused fires have been solved by investigators.

That backs what Pat Schneider, an assistant U.S. attorney in Arizona for the past 20 years who has experience on cases stemming from wildfires including the well-known Rodeo-Chediski Fire of 2002, told me for my June 12 story on this subject:

Finding the culprit is daunting for fire investigators, he said.

More than 70 percent of Arizona is federal land and the number of law enforcement officers is limited, he said. And wildfires believed to be caused by people are frequent - 142 fires of more than 100 acres in Arizona from 2003 to 2010, show data from the Southwest Coordination Center.

"Many times, the cases we are able to make and prosecute are when the suspect is caught in the act or soon thereafter, or because someone from the public helps as our eyes and ears," Schneider said. "The problem with fire, depending on how it burns, is that many times fire destroys a lot of evidence that was there."

The U.S. Attorney's Office in Arizona has handled just a few wildfire cases each of the past two years, he said. He didn't recall any prosecution of illegal immigrants in connection with wildfires.

• 16 percent — that’s how many of the “solved” fires in the Coronado National Forest were determined to be started by illegal border crossers.

That may surprise people one way or another. For those who contend most of these fires are started by illegal border crossers of smugglers, it might seem low. For those argue that blaming illegal immigrants for the fires is misguided, it may seem high.

Here’s the full text of the section of Peña's testimony where he addresses the causes of border fires in the Coronado National Forest:

“Wildfires occur near the U.S./Mexico border where there is heavy cross border traffic. During Forest Service investigations of these fires a great deal of information is collected, much of which is inconclusive or circumstantial in nature. A specific cause for the fire can be determined in some cases and in other cases, a specific cause cannot be determined. Forest Service investigations may or may not conclusively identify a person or persons responsible for the fire.

“We have been asked specifically if fires are related to cross border activities. What we can tell you is that from 2002-2011, 457 fires have been determined to be human-caused in the SW border area of the Coronado National Forest. Forest Service investigators have been able to identify the individuals responsible in 31 of those fires. Of those 31 fires, it was determined that undocumented aliens were responsible for starting 5.”