Retired Killeen, Texas, cop Greg Ebert knew there was something wrong with the nervous 21-year-old ammunition customer.

“He stands here and asks the manager, ‘what is smokeless powder?'” recalls Ebert, who works at Guns Galore.  “Well, my God, if you don’t know what it is, why would you buy six pounds of it?”

Thursday, police arrested 21-year-old Private First Class Nasser Abdo, stationed at Fort Campbell, Kentucky. U.S. Senator Kay Bailey Hutchison says he had prepared bombs and firearms for an attack on a Fort Hood-area restaurant frequented by military personnel.

Abdo has been absent without leave since the 4th of July weekend. And there was just too much about him that set off clerk Ebert’s alarms — little things. Nervousness. Odd questions. A large purchase of ammunition.

“He showed up in a taxi cab,” says Ebert. “That’s just kind of out of the norm.”

So, Ebert tipped off a friend at the Killeen Police Department. Investigators tracked down Abdo at the America’s Best Value Inn near the army base. There, Killeen Police Chief Dennis Baldwin says, “During the investigation, suspicious materials were located in his hotel room.”

Those suspicious materials included six canisters of smokeless gun powder, three boxes of ammo, a magazine for a 40-caliber hand gun and extremist Islamist materials.

What if Ebert had not made the phone call?

“We would probably be here today giving you a different briefing had he not been stopped,” says Baldwin.

Abdo is being held in the Killeen Jail until federal charges are filed.

Abdo had made national headlines for his fight for “conscientious objector” status.

A facebook page, deactivated Thursday around 1:30 p.m., sheds light on just how highly Abdo objected to a possible Afghanistan deployment. It is a message he expressed in a June 2011 interview with Nashville NBC affiliate, WSMV-TV. “What matters to me is that I did the right thing in my book,” says Abdo, “I refused to go to Afghanistan because it was against my Islamic conditions.”

Last year, Abdo was viewed as a peacemaker by anti-war activists, notes Alana Goodman in Commentary magazine: 

When Pfc. Naser Abdo applied for CO status last year, Iraq Veterans Against the War organization posted a message in support of him on its website, and asked readers to donate to his legal defense fund. And Kimber Heinz, a writer for Truthout, unluckily chose to profile Abdo in a 2010 article entitled, “One Year After Fort Hood: The Missing Story of Muslim Peacemaking.”

“We must lift up the stories and ongoing work of Muslim peacemakers like Naser Abdo,” Heinz wrote.

CNN and al-Jazeera also both featured glowing segments on Abdo’s quest to obtain CO status.

But there were others who immediately condemned Abdo’s attempt to dodge combat service. The American Islamic Forum for Democracy, an organization led by Dr. Zhudi Jasser, urged the military to reject Abdo’s request last year.

Baylor University Islamic Studies Professor Christian vanGorder says the foiled terror plot should not be linked to Islam.

“When we see these types of terrorist attacks committed in the name of Islam,” says vanGorder, “they don’t represent Islam any more than say for example a Christian would feel represented by people killing in the name of Christ.”

His comments resonated in the wake of the Norweigan mass-murders only days ago — perpetrated by a self-confessed neo-Nazi who proclaimed in a manifesto that Protestants should be forced to return to the Catholic Church and posted on Facebook that he is a Christian.

It was just a year and a half ago that alleged Fort Hood shooter and radical Muslim, Nidal Hasan, killed 13 people and wounded 32 in a shooting rampage on post. He bought ammunition at the same Killeen gun shop.

Police Chief Baldwin praised store clerk Ebert’s alertness — and said Abdo was fortunately stopped before anything could be carried out.

That is a message the community can learn from, the police chief said: “Stay vigilant – not in fear, but certainly vigilant about what’s going on around you. And again, don’t wait for someone else to pick up the phone to call if you see something suspicious.”

And after decades in law enforcement, Ebert is pleased that he has not lost his ability to sense when a person is up to something.

And that he was able to save a lot of lives with just one phone call.