By Alan D. Fischer

Tucson optics consultant Barbara Grant used science - not politics - to determine that law enforcement agents likely fired guns at the Branch Davidian compound near Waco, Texas, in the moments leading up to the building burning to the ground.

A November 2000 report said agents fired no shots at Branch Davidians that day in 1993.

Grant spent two years studying infrared tapes taken by the FBI between 11:18 a.m. and 12:15 p.m. on April 19, 1993, from a plane circling 4,000 to 6,000 feet above the compound.

A 51-day standoff between the Branch Davidians and federal agents ended that day after a fire engulfed the compound following efforts to drive the occupants out by using tear gas and demolishing portions of the structure. About 80 people died, and some survivors were severely burned.

Grant, speaking to about 50 people at Thursday's Arizona Optics Industry Association luncheon meeting, showed segments of the FLIR infrared sensor tape that recorded temperature variations at the compound, including several sequences of multiple, sequential high-temperature "flashes" aimed toward the building.

"I believe the most likely explanation of the flashes is gunfire," Grant said.

She said the series of flashes occurred periodically until about 12:10 p.m., when the compound burst into flames. Her research focused primarily on a multiple flash sequence at 11:28 a.m.

A report on the incident, released Nov. 8, 2000, by Waco Investigation Special Consul John C. Danforth, states "unequivocally" that "government agents did not shoot at the Branch Davidians on April 19, 1993."

Casey Stavropoulos, public affairs press assistant at the U.S. Justice Department in Washington, D.C., said late Thursday that she had no information on Grant's investigation.

"I don't have anything to comment on in response to what her findings are," Stavropoulos said.

A Justice Department representative said earlier this week that the agency stands behind the Danforth report's findings.

Other explanations of the flashes have included a malfunction of the FLIR sensor and heat from the sun glinting off debris at the compound.

The Danforth report states: "It is concluded with a confident level of certainty that of all of the analyzed flashes seen on FLIR videotapes from April 19, 1993, between 10:41 a.m.-12:16 p.m. are caused by solar or heat reflections from single or multiple objects.

"The results from this investigation have shown, with a confident level of certainty, that the flashes on the FLIR videotapes from April 19, 1993, between 10:41 a.m.-12:16 p.m. cannot form evidence of gunfire."

Grant said her study showed the sensor malfunction and debris reflection scenarios are far less likely to explain the infrared flashes than the muzzle flash of weapons. "I would discount the first one," she said. "For the second one, in our experiments we found glass gives a pretty awful reflection in the infrared spectrum - not like visual light, it appears as a vague glow, not like the flashes that appeared on the tape."

She said that debris would have to be shiny, elevated and precisely aimed at the FLIR sensor in the moving aircraft to work as an explanation for the heat flashes.

Grant said that unlike Danforth's report, she would not claim to be 100 percent certain of her findings.

"My mind is still open. If someone can come up with a better solution, I will be glad to consider it," she said. "I am saying this is the most likely conclusion."

"It was valid science," Arizona Optics Industry Association member Keith McLeod said of Grant's presentation. "It wasn't schlepping one side or the other. It was simply taking basic high school and college analysis to dismantle the FBI's position."

Kathleen Perkins, CEO and publisher of OpticsReport, said, "This is a fine example of how optical engineers can find thorough solutions to problems."

Grant, a 1989 University of Arizona Optical Sciences Center graduate, is an electro-optical engineer who specializes in radiometric measurement and data analysis. This involves the measurement of light and the analysis of data obtained from optical instruments. She has worked as a Tucson-based electro-optics consultant the past four years.

She said she was drawn to the Waco controversy and wanted to approach it from a technical, analytical angle, avoiding the emotion and politics that had crept into some other investigations.

"I stayed very much in the technical realm. There is more technology here than you can shake a stick at," she said. "I haven't accepted a dime of money from anyone. I wanted to make this as objective as possible."

Grant and local attorney Dave Hardy, who pursued a Freedom of Information Act suit for two years to get the FBI to surrender a copy of the FLIR tape, made their own infrared tapes of weapons firing at a local shooting range for comparison.

These tests at the Desert Trails Gun Club and Training Facilities showed that muzzle flashes could last four times longer than the government said was possible, and helped Grant show that muzzle flashes would appear on the 30-frame-per-second FLIR videotapes.