Man in Photo Could Be Key to Fire Investigation : Evidence: Suspects in Malibu blaze say he lent them a device to hook a hose to a hydrant. Mystery plumber or contractor has not come forward.

Two firefighters suspected of setting last year’s Calabasas/Malibu fire have told friends that a man pictured in last week’s Los Angeles Times may have key evidence to bolster their account.

But sources close to the investigation say the man has not come forward despite an avalanche of publicity, and investigators are not convinced that he could offer any significant information.

Steven R. Shelp and Nicholas A. Durepo, both of whom were volunteer firefighters at the time of last year’s blaze, have told investigators that they stopped a passing plumber as the fire was spreading and borrowed from him a device that allowed them to hook a garden hose to a nearby fire hydrant. At a news conference last week, Los Angeles County Sheriff Sherman Block questioned that aspect of their story, noting that investigators have been unable to locate the plumber.

In Saturday’s editions, The Times published a photograph of a man drinking from the hose, and Shelp has told his friends that the man in that photograph is the mystery plumber, who Shelp has said was driving a white pickup truck along Old Topanga Canyon Road and stopped to help. People close to Durepo say he has told them roughly the same thing, adding that the man might be a contractor rather than a plumber.

If their accounts are correct, the unidentified man in the picture could have evidence that would help corroborate the firefighters’ accounts of what happened Nov. 2.

The friends of Durepo and Shelp spoke on condition of anonymity because some work for area fire departments and say they fear for their jobs. The friends also cited a strict no-comment policy that lawyers for Shelp and Durepo have imposed on the two suspects and people close to them.

Although they have declined to discuss their case publicly, investigators doubt many aspects of the version of events told by Durepo and Shelp, sources familiar with the investigation say. They note that Shelp and Durepo failed lie detector tests (such tests generally are inadmissible in court because of their unreliability) and say that, during a break in their interviews with investigators, Shelp was overheard to say to Durepo: “Don’t sweat this. I won’t give you up.”

Block has said he is confident that the Sheriff’s Department has identified the right suspects. Meanwhile, the Los Angeles County district attorney’s office has scheduled three days of grand jury hearings for next week, and at least half a dozen people have been ordered to appear.

Details of the case came to light last week, and since then, investigators and prosecutors have engaged in a tense faceoff over how to proceed. While Block was publicly discussing some aspects of the case, Dist. Atty. Gil Garcetti was out of town and his office has generally declined official comment. However, sources there have expressed some doubts about the strength of the Sheriff’s Department case.

Block’s comments and those from other sources familiar with the investigation have dramatically increased the pressure on Garcetti to take decisive action in the case. If Garcetti chooses not to prosecute, there also is the possibility that the U.S. attorney’s office could accept the case because arson is a federal as well as a state crime.

Garcetti and Block have scheduled a meeting for today to discuss how to proceed in the case, sources said.

Times staff writer Josh Meyer contributed to this report.