Fire crews battle the July 5, 2005, blaze at Roy Martin Middle School at 28th Street and Stewart Avenue. Fire officials have various theories for why the number of arsons is rising. Photo by Craig L. Moran. A Las Vegas Fire Department firefighter puts on his air mask before moving in to fight a blaze set July 5, 2005, at Roy Martin Middle School in Las Vegas. The fire caused $7.5 million in damage to the school. Las Vegas had a total of $9.6 million in arson damage last year. Photo by John Locher.

Las Vegas and Henderson have seen a steady and dramatic increase in arson cases in the past five years, and experts say that an increase in insurance fraud may be to blame.

According to the FBI's Official Crime Report, 98 arsons were reported in Henderson in 2005 and 441 that year in the Metropolitan Police Department's jurisdiction.

In 2001, Henderson's 31 arsons were less than a third of its 2005 numbers.

In Las Vegas, 268 cases of arson were reported in 2001.

Although many Nevada municipalities see fluctuations that show no definitive trends, Henderson and Las Vegas see continuous gains.

Reno, the state's third largest city just behind Henderson, reported only 14 arsons last year, a five-year low.

Officials in North Las Vegas, whose population is approaching the 200,000 mark, reported 42, just two above the city's five-year low.

The national figures show a decline. Cities larger than 500,000 people saw a 10.6 percent decrease in arson cases from 2004 to 2005, according to the FBI.

A comparable percentage is not available for communities with fewer than 500,000 people, but arson was down 2 percent nationwide.

Still, fire officials say the FBI numbers don't tell the whole story.

Police departments report criminal arson cases to the FBI, but local fire departments often have different figures on arson cases.

Las Vegas Fire Department spokesman Tim Syzmanski said that Las Vegas city proper has seen an overall decrease in arson cases in the past 10 years, but their departmental figures fluctuate.

The city saw a 10-year high of 192 arson cases in 1996 and a 10-year low of 66 in 2004. There were 111 arsons in 2005.

The Clark County Fire Department, which covers county areas outside city limits, reports an increase over the past five years. There were 352 arson cases in 2005, compared to 136 cases in 2001.

Clark County Fire Department spokesman Bob Leinbach said he had no answer to why arson has increased for his department.

Because of July's Roy Martin Middle School fire, which caused $7.5 million in damage, Las Vegas saw $9.6 million in arson damage last year, the largest amount for any year or single incident since the Hilton arson caused more than $10 million in damage in 1981.

For Henderson, the numbers actually might be higher than the FBI says.

Henderson fire investigator Don Spellman said 133 arson cases were recorded in 2005, as opposed to the 98 that the FBI reports.

But that's because the FBI numbers include only criminal arson cases and not all intentionally set fires.

FBI spokesman Paul Bresson said the bureau stands by the figures, saying that any variation in numbers is negligible.

There is some debate about the reason for the rise in arson.

Fire officials claim the rise in Southern Nevada's population means a rise in crime, but population growth still hasn't kept up with the arson rates in Henderson and Las Vegas.

Insurance experts suspect a rising problem of vehicular arson is contributing to the increase.

Ray Unsell, special agent for the Nevada Insurance Crime Bureau, said it's common for people to get in over their heads in car payments and then try and torch the car to break free.

"My opinion here is that we have an image here of hitting it big, and everyone likes to drive big cars and sometimes they can't afford it," Unsell said.

Jim Denton, investigator for the Nevada Insurance Council, agrees with Unsell, adding that the rise in vehicular arson is directly linked to the rise in car thefts.

Las Vegas is second to only Modesto, Calif., in auto theft nationwide.

In most cases, vehicles are reported stolen before they are burned.

Denton said a criminal might steal a car to commit another crime and will burn the car to destroy any evidence.

Denton said that although there usually isn't much damage caused by vehicular arson, it still is a serious crime. He said that such fraud causes insurance premiums to be higher for honest policyholders.

Spellman said Henderson is proud of its 30 percent solve rate for arson cases, compared to 19 percent nationwide.

Las Vegas fire officials report a 22 percent solve rate.

Clark County officials did not have the information available.

Officials say arson cases are not easy to solve because cases largely are based on circumstantial evidence, such as late bills, financial information and holes in alibis.

"It's easy to prove that arson occurred," Spellman said. "It's harder to prove who did it."