DALLAS (AP) -- A Texas agriculture inspector failed to note that a peanut plant at the center of a national salmonella outbreak was operating without a state health department license, despite at least three visits in the years before hundreds of people got sick, according to interviews and documents obtained by The Associated Press.

The inspector responsible for certifying the plant to process organic products noted after each visit that the plant operated by Peanut Corp. of America had such a license when it didn't. Noting that the plant failed to obtain a license would have alerted the state health department, which for years had no record of the plant and didn't send its own inspectors there until recently.

When the plant was finally inspected earlier this year, Texas health officials found dead rodents, rodent excrement and bird feathers in a crawl space above a production area, leading them to order a recall of all products the plant had shipped since 2005.

Tests have since shown that ground peanuts at the Plainview plant were contaminated with the same strain of salmonella that sickened more than 650 people, is suspected of causing at least nine deaths, and led to one of the largest product recalls in U.S. history. Salmonella has also been detected in peanut samples from a Georgia plant operated by Peanut Corp., which has filed for bankruptcy amid fallout from the outbreak.

Texas Department of Agriculture spokesman Bryan Black said if the lack of a license had been properly noted, the department would have denied it organic certification and notified the Department of State Health Services. The inspector, Gaylon Amonett, was fired on Feb. 13, the day after state health officials ordered the recall.

"We trust our inspectors to do their jobs," Black said. "Any time they do not follow the protocol, it is inexcusable."

Because the Plainview plant was not licensed, state health officials have said they had no record it existed and never sent their own inspectors to the facility to check for possible food safety problems. All food manufacturers in the state are required to obtain a license from the state health department.

Amonett, a 22-year TDA employee who worked out of the agency's Lubbock office, acknowledged that he checked "yes" to the question of whether the Plainview plant had records showing it was in compliance with health codes on worksheets he completed for inspections in 2005, 2006 and 2008.

The reason he checked "yes" the first time, he said, was because a plant manager told him an application for state health department licensing had been completed and was in the hands of Peanut Corp. officials at the company's headquarters. He said he continued to check "yes" in succeeding years because he assumed that the license was granted.

Amonett said the matter was his "only mistake" in his years as an inspector. Agriculture department records show that he received a merit raise on Jan. 1.

"It's an inadvertent mistake, and I'm sorry for it," he said.

Jack McCasland, environmental inspector for the Plainview-Hale County Health Department, said plant officials led him to believe the licensing process was under way when he visited the facility before it opened.

"To be honest, I never really thought to follow up on it," McCasland said. "It just never occurred to me that they wouldn't be (licensed)."

Organic certification allows companies to market products as organically grown or produced. Processors must meet standards set by the U.S. Department of Agriculture and are monitored by a USDA-accredited entity. The Texas Department of Agriculture has served as a certifying agency since 2002.

If the Plainview plant hadn't been undergoing organic certification, the state agriculture department wouldn't have inspected it.

In a memo about the Plainview matter, TDA assistant general counsel Jim Pollard wrote that Amonett was trained as an organic inspector in 2004. Under agency rules, inspectors are required to make sure a company's licenses and other records are complete and current. The memo, obtained by the AP through a request under the Texas Public Information Act, cited the three inspections by Amonett.

TDA declined to release the inspection reports, contending that they are exempt from disclosure under the information act.

Although food safety is technically not part of the organic certification process, the salmonella outbreak has prompted the USDA to direct organic certifying entities to report any health or safety violations to the appropriate government officials.

"While we do not expect organic inspectors to be able to detect salmonella or other pathogens, their potential sources should be obvious from such evidence as bird, rodent and other animal feces or other pest infestations," the directive stated.

Associated Press writer Betsy Blaney contributed to this report from Lubbock, Texas.