NACOGDOCHES, TEXAS ? Rain-drenched searchers trudging through the forests and fields of east Texas found computer components complete with serial numbers Thursday as they scoured the muddy earth for clues to what caused the space shuttle Columbia’s destruction.

Investigators also checked reports of debris in California and Arizona, but shuttle program manager Ron Dittemore said late Thursday that as far as he knew, no shuttle parts had been confirmed west of Fort Worth, Texas.

“We’re still looking for that elusive missing link,” he said.

So far, none of the more than 12,000 individual pieces found in a field stretching across east Texas and Louisiana has provided the critical answers NASA is seeking.

On Thursday, searchers found mostly small pieces of debris, officials said. Among them were 10 pieces of computer components uncovered near Chireno, several with visible serial numbers on them, Nacogdoches County Sheriff Thomas Kerss said.

The components were believed to be from the shuttle, though their significance to the investigation was not immediately clear.

The shuttle was made up of about 2 million parts, many of which shattered into pieces as small as a nickel. The key pieces for NASA’s investigation will be the data recorders, certain tiles and parts from the left wing where sensors showed a temperature rise before the shuttle broke up Saturday over Texas.

With heavy rain falling Thursday across the debris field, experts worried that sensitive pieces could end up buried in mud or degrade if left exposed.

“Obviously the weather is a significant factor for us, but we are continuing on,” Nacogdoches County Judge Sue Kennedy said.

Nacogdoches County, Texas, Sheriff's Deputy Rodney Whittington logs a piece of debris found in a field east of Nacogdoches, Texas, believed to be from the space shuttle Columbia. Heavy rains Thursday in the area are hampering the search for debris by Whittington and others.