And in the days following the deadly blaze that burned more than 91,000 acres and destroyed more than 1,000 structures after igniting on Oct. 25, 2003, law enforcement officers received hundreds of leads regarding the fire.
"We were all focused on who was involved in it," said Sgt. Joe Palomino from the witness stand inside the San Bernardino Superior Courthouse.
Palomino, who was a detective with the San Bernardino County Sheriff's Department in 2003, testified on the 17th day of the trial surrounding the Old Fire. He was assigned to the sheriff's homicide division and was on a team that investigated the Old Fire.
Then, in January 2004, someone contacted the sheriff's department with information that put Rickie Lee Fowler - the suspected arsonist - on their radar.
Fowler, 30, of San Bernardino has been charged with five counts of murder and special circumstances, which allow prosecutors to pursue the death penalty if he is convicted. Prosecutors say five residents in burn areas died from heart attacks that were caused by the stress of evacuation and threats to homes and belongings.
Defense attorney Donald Jordan started his case Monday, calling to the witness stand several people who were loosely connected to Fowler and the incidents surrounding the fire.
Five witnesses testified about background details like the suspect vehicle and day-of-the-fire schedules.
One of the witnesses Monday was Dean Raef, whose name came up early in the Old Fire investigation.
Officials suspected Raef might have been involved in starting the fire and in January 2004 they brought him in, interviewed him and eventually let him go. He was never arrested.
Raef testified that he had nothing to do with the Old Fire and that he had only met Fowler three times before the fire started.
During one of those meetings, Raef said, Fowler pulled a gun on him and demanded a ride down the mountain.
Supervising Deputy District Attorney Robert Bulloch rested the prosecution's case on Monday.
Reach Lori via email or call her at 909-483-9378, or find her on Twitter @IEcourtsNow