Evidence eludes investigators in Oakland Fire marshals' high-tech gear just isn't enough

November 07, 1991|By Knight-Ridder

OAKLAND, Calif. -- To the uninitiated, the 50-by-50-foot area where the great Oakland fire is believed to have started looks like nothing more than a patch of charred hillside.

But to veteran fire investigators, that blackened square is a page of arcane text. Written upon it in the physical language of fire is the story of the first few moments of one of the worst conflagrations in U.S. history.

Through a combination of new scientific testing techniques and old-fashioned sleuthing skills, investigators often can decipher detailed chronologies from bits of ash and debris. It is slow reading, however, and is best done on hands and knees while looking through a magnifying glass.

A twig more blackened on the east side than the west offers a clue to what direction the fire was moving when it passed a particular spot. A tree stump with a burn line sloping upward means the fire was climbing the hill; had it been burning downward, the burn line would have been parallel to the ground. The degree to which available fuel was consumed indicates the heat of the blaze and the play of the wind.

The 45-member Governor's Special Arson Task Force, which includes some of the nation's top fire investigators, has determined more than the origin of the inferno. State Fire Marshal James McMullen, who heads the task force, says it also has determined that the fire was not sparked by causes such as lightning or electrical lines.

It is officially designated as "suspicious," which assumes that it was accidentally or deliberately set by a person. Precisely how and by whom are questions the charred text has not yet answered. One possibility is that it was sparked from embers in a pit barbecue that lies within the zone of origin, but investigators say they have not been able to determine if any live coals were in the pit before the fire.

"Arson is the most difficult crime of all to investigate and prosecute," McMullen said in an interview. "It destroys its own evidence."

Experts say that is especially true of wildlands fires like the one here that killed 25 people and destroyed more than 3,000 homes. Blazes confined to a single building, even if it is a towering high-rise, tend to leave many more clues.

"After a building fire, you almost always have evidence left," says RonWolters, assistant special agent in charge of the western region of the U.S. Treasury Department's Bureau of Alcohol, Tobacco and Firearms, the federal government's lead agency in arson investigations. "Physical characteristics, char patterns, even things like what metals melted, are all indicators of the nature of the fire. But if it's a wildlands fire that you start with ~~TC match, you're not going to have anything left."

Thus far, that's a major impediment to determining the cause of the Oakland fire, investigators say.

Fred Strayhorn, chief of the arson and bomb investigation division of the State Fire Marshal's Office, says no physical evidence has been found at the site of origin, even though investigators have gone over every square inch of the area on their hands and knees with magnifying glasses and magnets.

Still, Strayhorn, whose 33 years of professional experience includes 15 years as a wildlands fire investigator for the California Department of Forestry, says he is optimistic that investigators will be able to piece together what caused the brush fire on Oct. 19 that led to the inferno of Oct. 20.

If so much as a shred of physical evidence is found, the investigation might be greatly advanced. William Dietz, chief of the forensic section at a secret ATF laboratory in Contra Costa County, says even a partially burned match or a cigarette butt could provide crucial clues of what happened.

Dietz, who gave a reporter a tour of the lab on condition its location not be disclosed -- "Not everybody loves us" -- says enormous gains have been made in using state-of-the-art technology to unravel fire mysteries.

Should that missing cigarette butt be found, for example, it could be tested for saliva, which can indicate the blood type of the person it came from. Failing that, the stub might provide a fingerprint that could be lifted by an argon ion laser.

The laser sends out a blue-green wavelength of light that illuminates minerals and enzymes that represent approximately 1 percent of human perspiration. So sensitive is the machine that a complete fingerprint can be determined from the pattern of the deposits.

Another weapon in the arson investigator's arsenal is infrared spectrophotometry, which uses infrared light to determine the chemicalbonds of various compounds. From the bonds, investigators often can determine specific chemicals used to start fires.

Gas chromatographs, which separate chemicals into compounds, also are used, as are mass spectrometers, which break chemicals down to individual ions that can be identified by the tracks their electrical charges leave on a graph. By identifying the ions, investigators often can identify the chemicals they formed.

Still another tool, one recently pioneered by Dietz, is a technique

called "passive diffusion." For that procedure, a chunk of soil or swatch of fabric that was doused with a flammable liquid prior to the fire is placed in an airtight can. Fumes from the can are absorbed by charcoal, then extracted for testing.

In room after room, the secret lab contains a dazzling array of sophisticated equipment. Yet all last week, Dietz sat just a few miles from the ashes of a huge fire and had no work to do on it. With no physical evidence, there was nothing for him to test.

"The problem is that it does not take a whole lot to set off dry grass," he said. "Somebody could drop a few coals from their fireplace and that would be it."

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