The man accused of starting a raging California wildfire that killed five firefighters pleaded not guilty to new arson charges Monday before the start of his long-awaited preliminary hearing.

Raymond Lee Oyler, 36, is charged with five counts of first-degree murder, 17 counts of using an incendiary device and 23 counts of arson, including the deadly Esperanza Fire. He was arrested Oct. 31 after a wind-whipped fire raced through the foothills near Banning, about 90 miles east of Los Angeles.

Oyler appeared in court wearing a black suit and gray tie. He was not handcuffed.

"The evidence is going to show that there was a series of fires, all started by Mr. Oyler, that the devices that Mr. Oyler used had distinct similarities and that there's an evolution in the devices," said Deputy District Attorney Michael Hestrin. "There was also an evolution of locations and terrain that the defendant was choosing as regards to each fire."

Oyler's sister, Joanna Oyler, and his girlfriend, Crystal Breazille, were excluded from the courtroom because prosecutors plan to call them as witnesses.

Firefighters Jason McKay, 27; Jess McLean, 27; Daniel Hoover-Najera, 20; Mark Loutzenhiser, 43; and Pablo Cerda, 23, were overrun by flames on Oct. 26 while protecting a home. McKay, McLean and Hoover-Najera died at the scene. Loutzenhiser died several hours later and Cerda died several days later. Some 10,000 people attended their memorial service.

Oyler was originally charged with 11 counts of arson and 10 counts of using an incendiary device, but prosecutors filed 19 new counts against him last week, saying they have linked him to 23 arson fires in all.

Oyler was initially charged in a string of fires that began in June, but the amended complaint filed last week adds charges for multiple fires in May and June, and one new fire apiece in July and September.

Prosecutor Michael Hestrin said the hearing could last several days, with at least 20 witnesses taking the stand.

An evidence log obtained by The Associated Press last week shows investigators recovered pieces of a cigarette-and-matches incendiary device from at least four of the new blazes.

A sheriff's report also obtained by the AP last week said Oyler's cousin told investigators the suspect spent an entire night one week before the deadly blaze "casing the area" for a good arson location.

Investigators say Oyler's girlfriend also told them he wanted to start a fire as "a diversion" so he could get his pit bull out of the Banning Animal Shelter.

Defense attorney Mark McDonald said the cousin was not a credible witness because she had a feud with Oyler and his closest relatives. McDonald said Oyler's girlfriend was badgered by investigators and now denies telling them any of the information listed in the report.