Most wildfires are caused by human activity, and government statistics show that people were faulted for 5,208 wildfires in Southern California in 2008, the highest number since at least 2001. Between 2006 and 2008, Southern California was the only region of the country to see a significant jump in the number of wildfires blamed on people.
"We are going to find out what we can and present it to the D.A.," Los Angeles County sheriff's Lt. Liam Gallagher. "We are considering it a murder investigation."
Still, very few of the forest fires lead to criminal or civil cases. The U.S. Forest Service recorded nearly 400 arson wildfires since 2005, records show.
Firefighters paused in their battle against the fire Friday to pay their respects to two fallen comrades whose deaths have triggered the investigation.
Hundreds of weary firefighters who have slogged on the front lines for the past 11 days took off their caps and helmets and bowed their heads at a tribute for Capt. Tedmund Hall and Specialist Arnaldo Quinones, held before dawn at the command center in the foothills near the flames.
The men helped save about 60 members of an inmate fire crew Sunday as flames approached their camp by setting a backfire that allowed the group to get to safety, said Los Angeles County Fire Capt. Glenn Goulet. The pair died when their truck plunged 800 feet down a steep mountain road.
The blaze was 42 percent surrounded Friday, authorities said. It has charred more than 60 homes and burned three people.
Authorities blocked access to the crime scene, a charred area of scrub and trees off the side of the Angeles Crest Highway, as they analyzed incendiary material reported to be found there.
Investigators will pick through clues at the scene, try to establish a likely motive for the arsonist, then predict the characteristics and traits of the unknown offender as they look to make an arrest.
Timothy Huff, a former profiler with the FBI who has interviewed more than 100 convicted arsonists, said the typical profile of an arsonist is that of a white man aged between 15-25. The most common arson motivation is revenge, Huff said, with offenders seeking to harm individuals, groups, institutions or society in general.
Riverside County Deputy District Attorney Michael Hestrin, who has prosecuted wildfire arson cases, said it depends what kind of evidence investigators gather in the current fire to make a decision to file murder charges.
"An arsonist could be responsible for all the consequences that his act set in motion," Hestrin said. "He unleashes this disaster and men died in an effort to save people from ruin or injury. He could be liable for those deaths."
Firefighters have set up a makeshift memorial for the fallen firefighters at the base camp. An American flag and a trio of firefighters' tools were flanked by photos of the firefighters - smiling in uniform - and surrounded by wreaths. Nearby, firefighters had scribbled messages on sheets of paper tacked to a large wooden board.
"God bless you brother," one had written. "Never forgotten," wrote another.
Those who knew Hall, 47, and Quinones, 35, said they were both motorcycle enthusiasts who were devoted to their jobs. Quinones was eagerly awaiting the birth of his first child and had recently turned down a work assignment, Goulet said.
"He said 'Hey, my baby's coming. I want to be there.' So he stayed at camp," said Goulet, who added Quinones had a motto on the back of a tattoo that said, "First in, last out."
Associated Press writers Greg Risling, Thomas Watkins and Raquel Maria Dillon contributed to this report.