RIVERSIDE, Calif. — A jury convicted an auto mechanic toay of murdering five federal firefighters by setting a wildfire that overran them as they defended a home in a rural Southern California mountain community.

Raymond Lee Oyler, 38, was found guilty of five counts of first-degree murder. Because he committed multiple murders and did so while committing another felony — arson — he could face the death penalty in a trial phase beginning Tuesday.

Relatives of the victims and the defendant sobbed as the verdicts were read in Riverside County Superior Court.

Oyler was also found guilty of 20 counts of arson and 17 counts of using an incendiary device. The jury deadlocked on three arson counts, and a mistrial was declared on those charges.

The verdicts followed a monthlong trial with testimony by arson investigators, fire experts and several of Oyler's relatives.

The fatal blaze, now known as the Esperanza Fire, roared to life as fierce Santa Ana winds swept through valleys and mountains about 90 miles east of Los Angeles.

The crew of San Bernardino National Forest Engine 57 was overwhelmed after deploying to protect an unoccupied house perched at the top of a steep drainage in the San Jacinto Mountains. Three firefighters died there and a fourth died soon after at a hospital. The fifth died five days later, the same day Oyler was arrested.

Some 10,000 people attended the memorial service for Jason McKay, 27; Jess McLean, 27; Daniel Hoover-Najera, 20; Mark Loutzenhiser, 43; and Pablo Cerda, 23.

The fires Oyler was charged with spanned a period from May 16, 2006, to the Esperanza Fire on Oct. 26, 2006. All were set in rural Riverside County.

Much of the trial focused on differences in the types of incendiary devices found at various fires. Arson investigators recovered paper matches, a "layover" that consisted of matches balanced on a single cigarette and more elaborate devices made up of wooden matches grouped around a cigarette and secured with duct tape or a rubber band.

Oyler's DNA was found on "layover" devices used to start two fires in June, but not on ones recovered at other fires.

Prosecutor Michael Hestrin told jurors that the variations in the devices showed that Oyler was experimenting with different designs and learning from his mistakes.

Hestrin pointed out that the first fires died down almost immediately, but as time went on the blazes covered more and more acreage. Arsons just prior to the Esperanza Fire burned more than 2 square miles of land and the fatal fire charred 70 square miles of terrain.

Defense attorney Mark McDonald told jurors in his closing argument that his client likely started 11 of the 23 fires — but not the fatal one.

He said changes in the design of the incendiary devices indicated more than one arsonist and he presented a DNA expert who said she found partial genetic material from another unknown male on a device similar to the one used to start the Esperanza Fire.

The fatal blaze began on a hillside in the town of Cabazon and spread quickly from a valley floor up the north side of the mountains to the widely dispersed rural community of Twin Pines. The blaze destroyed 34 homes and 20 outbuildings.