Pentagon Suspect is Muslim Marine Corps Reservist

Uh oh.

The man in custody for carrying a backpack with "suspicious items and products" inside Arlington National Cemetery overnight is a U.S. Marine Corps reservist, military and law enforcement sources tell Fox News.

Yonathan Melaku, a Lance Corporal Marine corps reservist who lives in Virginia and who is Muslim, has been identified as the suspect in custody, Fox News has learned.

Sources close to the investigation also said a notebook believed to belong to the man was found containing threatening phrases like "Al Qaeda," "Taliban rule" and "defeated coalition forces."

Authorities said Friday they are investigating the man, whom they did not name, after he was found inside Arlington Cemetery overnight when the cemetery was closed.

FBI special agent Brenda Heck said during a press conference Friday that the man, described as in his 20's, had a backpack containing a "non-explosive, unknown material" that she said will require further investigation.

"The products in the backpack are inert," Heck said, though she described its contents as suspicious.

Though the man was "not forthcoming" when taken into custody, Heck said authorities later found his red 2011 Nissan near the Pentagon. She said authorities found "no suspicious activity" related to the vehicle.

Melaku, who lives in Alexandria, Va., joined as a reservist in August 2007 but military officials say he never deployed to Iraq or Afghanistan.

Law enforcement officials also told Fox News that police found five pounds of a substance labeled ammonium nitrate inside the backpack -- field tests, however, came back negative.

Heck would not confirm reports that a notebook was found, saying only that the investigation is still unfolding.

That whole Muslim outreach thing is really paying off, isn't it?