NACOGDOCHES, TEXAS ? Despite gathering more than 12,000 pieces of debris from the shuttle Columbia, a NASA official said Wednesday none of the pieces provided critical answers for why the shuttle broke up.

“We do not have any red-tag items,” said Ron Dittemore, shuttle program manager, referring to items engineers have identified as crucial to the investigation into the cause.

He said those items would include parts of the left wing, data recorders and certain pieces of insulation and tiles.

The widening search now extends from Louisiana to California.

In Texas alone, officials have identified 38 counties with debris, while pieces have turned up in two dozen Louisiana parishes. And NASA investigators are checking California and Arizona for debris as well.

“The scale makes it unprecedented,” said Dave Bary, a spokesman for the Environmental Protection Agency, which is overseeing the collection of debris. He noted that even in other major disasters — the attacks on the World Trade Center and the Pentagon, the explosion of space shuttle Challenger — the recovery sites were restricted to a central location.

In this case, “the debris field is so large — covering so many counties — I can’t think of anything historically that would compare to this,” he said.

That could delay meaningful analysis of those parts that have been collected — and what role they might have played in the disaster, NASA spokesman Rob Navias noted.

“We have to put the puzzle together before we see what the mosaic looks like,” Navias said.

The shuttle was composed of about 2 million parts, many of which shattered into pieces as small as a nickel.

Bill Waldock of Embry-Riddle Aeronautical University in Arizona said any of the craft’s 20,000 insulating tiles or metal components from the left wing would be significant.

At least two possible wing sections have been discovered in east Texas, although authorities did not know from which side of the shuttle they came. A robotic underwater camera was brought in Wednesday to help search a reservoir along the Texas-Louisiana border where there were reports of debris the size of a small car falling.

Waldock said some pieces — such as the nose cone, found Monday in east Texas — could help investigators rule out other potential causes of the disaster. “It didn’t look like the nose cone had much thermal damage at all; it’s not even really scorched,” he said. “It means that area was not exposed to the high temperatures.”

Because of bad weather Wednesday, the Forest Service opted not to ferry the nose cone out of the area by helicopter. Instead, a road was hewn through the forest and the cone was loaded onto a truck.

Federal prosecutors, meanwhile, were cracking down on accused looters. Two east Texas residents were charged with theft of government property for allegedly taking a circuit board and a piece of thermal insulating fabric. They could face up to 10 years in prison. Amnesty was offered through Friday evening for anyone else who handed over shuttle parts.