A 2-foot-long section of one of Columbia's wings found near Fort Worth is the most significant discovery yet in the search for clues to the shuttle's destruction.

The wing section was recovered at the far western edge of the known debris field, which stretches more than 200 miles from Fort Worth across East Texas and Louisiana. It wasn't immediately known if it was part of the important left wing, where several heat sensors failed in the shuttle's final moments.

"Examining where debris fell and where it was gathered is going to be very important as far as piecing the puzzle together as far as what happened at what altitude," shuttle program manager Ron Dittemore said Friday.

The shuttle was 16 minutes from a landing in Florida when it broke apart over the Southwest, killing all seven astronauts. Dittemore said Friday that no shuttle debris had yet been confirmed west of Texas.

The wing section recovered has 18 inches of wing structure and 26 to 27 inches of carbon-composite panel, which reinforces the leading edges of space shuttle wings for thermal protection during the searing heat of atmospheric re-entry, which reaches as high as 3,000 degrees.

Since the Columbia broke apart high over Texas on Feb. 1, NASA has focused on the left wing, where sensors had showed rising temperatures before failing entirely. Authorities planned to take the recovered wing section to a military installation in Fort Worth to inspect it.

In East Texas, searchers prepared to return to Toledo Bend Reservoir along the Louisiana state line to examine several large objects that sonar scans had located. Area residents had reported seeing falling debris the size of a compact car.

Buoy markers were placed where searchers believe debris may be resting on the lake bottom, but gusty winds kept divers from entering the water, officials said. A Forest Service spokesman said dive teams would return to the lake Monday.

Also Friday, an amnesty deadline ended for scavengers who picked up parts of the shuttle.

U.S. Attorney Matthew Orwig said response to the amnesty was overwhelming, with hundreds of pieces turned in since it began Wednesday. Federal prosecutors said anyone found with shuttle debris after Friday would face prosecution.

Two people charged earlier for allegedly keeping shuttle pieces face up to 10 years in prison if convicted.

Nacogdoches County Sheriff Tom Kerss said that once the deadline passed he would give the FBI about 75 names, compiled from tips by residents, of people who might have shuttle parts.

"We will have some search teams begin visiting flea markets," he said.

Searchers on foot again fanned out through the East Texas pine forests, helped by dry weather Friday.

Among the most important targets they were seeking was a device that allows for the encryption of communication between the shuttle and NASA controllers. A NASA spokesman in Houston, John Ira Petty, said Friday that NASA feared the technology could be used "to send bogus signals to the shuttle."

"We are searching for all debris. Certainly we would like to recover this one," Petty said.

The discovery of the wing piece — about 250 miles from Toledo Bend Reservoir — underscored the size of the Columbia debris field and could indicate an increase in attention on its western fringe.

Michael Kostelnik, a deputy associate NASA administrator, said NASA believes there is "a substantial amount of material" around Fort Worth and up to 150 miles west and northwest of the city.

In all, more than 12,000 individual pieces of debris have been found and their locations cataloged, officials said.

The pieces could arrive as early as Tuesday at Kennedy Space Center in Florida, where they will be laid out in a storage hangar on a grid marking off the entire shuttle, NASA spokeswoman Lisa Malone said.

"It will help put together what caused the accident," Malone said.