KILLEEN, Texas — Ultimately, it was the keen eye of a Texas gun shop clerk that helped authorities find an AWOL soldier who’d stashed bomb-making material in his nearby motel room for a planned attack on Fort Hood soldiers.

The tip that led Killeen police to Pfc. Naser Abdo on Wednesday prevented what could have been the second terrorist attack on the Army post, following a 2009 shooting rampage in which an Army psychiatrist is charged with killing 13 people. Earlier this year in Texas, a shipping company that told the FBI about a suspicious order for a chemical explosive foiled an alleged plot to blow up former President George W. Bush’s Dallas home.

The enduring lesson for a post-9/11 world: America’s work force plays a crucial role in preventing potential terror attacks.

“A vigilant public and informed local law enforcement make it much more complicated for people wishing to carry out attacks to do so,” said John Cohen, principal deputy counterterrorism adviser at the Homeland Security Department.

Federal programs in play

Federal and local law enforcement agencies have established programs over the past decade that encourage the public to report suspicious activity, and tips from businesses have led to multiple high-profile arrests.

Abdo, 21, who went absent without leave from Fort Campbell, Ky., early this month, was arrested Wednesday at a motel outside Fort Hood and charged with possession of an unregistered destructive device. Police say he was perhaps only a day away from unleashing bombs in a restaurant frequented by soldiers and attacking the Army post.

Abdo’s alleged plan was cut short when Guns Galore employee Greg Ebert became suspicious after the soldier acted oddly while purchasing smokeless gunpowder, shotgun ammunition and a semi-automatic pistol magazine. Ebert’s call to police and the soldier’s subsequent arrest was a proud moment for employees of the store — the same place Maj. Nidal Hasan bought a pistol used in the Fort Hood shooting spree two years ago.

Store clerk Dave Newby said Hasan’s purchase, while legal, devastated store workers and put everyone on higher alert.

“I think we all changed,” he said. “It was terrible. We thought about coulda, shoulda, woulda.”

Ebert noted this week that although there was “nothing extraordinary” about Abdo, he saw just enough to make him suspicious.

The retired police officer said Abdo arrived at the Killeen gun shop in a taxi — unusual for the Central Texas town — and proceeded to buy 6 pounds of smokeless gunpowder, while asking what it was. Abdo didn’t say much as he paid in cash, and he didn’t bother to collect his change or a receipt before returning to the waiting taxi.

“Now, he hasn’t done anything unlawful — it doesn’t prevent me from being curious,” said Ebert, who retired from the police force last year.

Individuals must act

Federal authorities say actions like Ebert’s can keep America safe.

“The willingness of an individual to contact law enforcement about an event or incident that may be indicative of a possible threat is vital to our mission,” FBI spokesman Paul Bresson said. “It may turn out not to be a threat but at least we have the opportunity to check it out.”

Other business tips have been credited with preventing disaster.

A clerk at a Circuit City store in New Jersey told police in 2006 that customers had asked him to make a DVD out of video footage of them firing assault weapons and screaming about jihad. The FBI later tracked six men, now known as the Fort Dix Six, who plotted to kill soldiers in a raid at the Fort Dix military base in New Jersey.

Earlier this year, two companies — Carolina Biological Supply Co. in North Carolina and Con-way Freight in Lubbock — contacted federal and local authorities about suspicions each had surrounding a purchase by Khalid Ali-M Aldawsari, who has been charged with attempted use of a weapon of mass destruction and schedule for trial later this year.

Federal authorities said Aldawsari bought explosive materials online and planned to hide them inside dolls and baby carriages to blow up dams, nuclear plants and Bush’s home. A former Texas Tech University chemical engineering student from Saudia Arabia, Aldawsari was arrested after the North Carolina company reported $435 in suspicious purchases to the FBI.

The freight company notified Lubbock police and the FBI with similar suspicions because it appeared the order wasn’t intended for commercial use. Con-way Freight spokesman Gary Frantz said since Sept. 11, 2001, the company has worked with local, state and federal authorities to develop training programs employees participate in at least once a year.

“I think we can be a force multiplied, which is a term often used by law enforcement, where private industry serves as additional eyes and ears to help authorities to uncover these activities to protect the public,” Frantz said.

Carolina Biological Supply spokesman Keith Barker said his company has procedures to closely monitor orders involving “chemicals of a high degree of hazard.”

“We’ve taken it upon ourselves to be vigilant,” Barker said.

Operation Tripwire

Meanwhile, “Operation Tripwire” is an FBI effort that asks certain businesses and industries — such as airlines and cruise ships — to look for and report suspicious behavior. The Department of Homeland Security has a national “If You See Something, Say Something” public awareness campaign that works with businesses and groups, such as the National Basketball Association, to promote public vigilance.

Some local law enforcement agencies also have partnered with businesses. New York Police Department detectives have asked thousands of companies to be on the lookout as part of “Operation Nexus.”

“In a sense we don’t know what we deter,” because people don’t commit crimes and get arrested, said Paul Browne, spokesman for the nation’s largest police department. “But by making these things harder, and by educating people who may become unwitting players in terrorist plots, we hope to have that deterrent impact.”

The Los Angeles Police Department created “iWatch,” which uses brochures, public service announcements and meetings with community groups to provide advice on how to detect and report suspicious behavior.

LAPD Cmdr. Blake Chow said the program is augmented by a web-based system that lets private businesses and security firms exchange information about suspicious activities. The intelligence gleaned with these systems, along with phone tips, has helped disrupt the financing of suspected overseas terrorist organizations, he said.

“The general public is the ones that go to the same place every day to work, they know their neighbors,” Chow said. “We rely on them to tell us if they see something or an individual’s activities that seem out of place.”

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Associated Press writers Betsy Blaney in Lubbock, Colleen Long in New York City, Eileen Sullivan in Washington and Thomas Watkins in Los Angeles contributed to this report.