June 17, 2011 -- A Marine Corps Reserve lance corporal who was carrying suspected bomb making materials and pro-al Qaeda literature was arrested in Arlington National Cemetery early this morning, triggering a bomb scare that snarled Washington's morning rush hour. The FBI, however, determined that the material in the man's backpack was harmless.
"There was not a device and the products found are determined right now to be inert," said Brenda Heck, special agent in charge of counterterrorism for the FBI.
The material in the suspect's backpack tested negative as a potential explosive, sources said.
Sources told ABC News earlier that the backpack contained what was believed to be ammonium nitrate and spent ammunition for an automatic weapon. The material was reportedly contained in four large ziplock type bags.
Sources also said there were pro-al Qaeda statements found in a notebook that contained mostly notes for a financial class. There was also was a page containing words "al qaeda," "Taliban rules," "mujahidin" and "defeated coalition forces."
The suspect was identified as Yonathan Melaku, 22, of Alexandria, Va. U.S. Park Police said no charges have been filed against him yet.
Melaku is a naturalized citizen and lance corporal in the Marine Corps Reserve, 4th engineer batallion out of the Baltimore, Md.
He joined the Reserve on Sept 4, 2007, according to the FBI, and is listed as a motor vehicle operator with Combat Engineer Support Company. He had been awarded the National Defense Service Medal and the Selected Marine Corps Reserve medal.
"We are told he had a backpack with five pounds of something labeled ammonium nitrate but as of this juncture, has not passed the test that indicates explosive capacity," New York City Police Commissioner Ray Kelly said today, when asked about the arrest. "It is too early to, I think, draw any conclusions but the investigation obviously is going foward with the federal authorities."
Sources say they haven't found any ties to a terrorist organization.
Police and the media congregated at Melaku's home in Fairfax County, Va. where two people were seen being questioned by authorities and FBI agents. The FBI and Fairfax police were seen huddling in groups and putting police tape to prevent people from entering the area. They went into the townhouse with bomb technicians without a search warrant under the "public safety hazard" issue.
An FBI spokesman would not confirm whether the house was indeed Melaku's or his parents' residence, but did say it's connected to the suspect and there was no safety hazard.
Melaku allegedly told police in Arlington when he was captured that there were other "devices" in the area and also the location of his vehicle. But the FBI said there was no reason to believe other individuals were involved and they believe the suspect acted alone.
Police were investigating a vehicle, a red 2011 Nissan, that contained materials authorities were examining to determine if it was a bomb or other weapon. The material was reportedly neutralized, according to law enforcement spokesmen at the scene.
There are two main types of ammonium nitrate, agriculture and blaster's grade. Ammonium nitrate for agricultural use is widely available but is of a chemical composition that will not easily detonate. Blaster's grade ammonium nitrate is used widely in mining and blasting. It's sale is under license and carefully monitored.
The Pentagon and the surrounding areas were closed to traffic this morning, creating a commuting nightmare.
Suspect in Custody After Pentagon Bomb Scare
Park Police Sgt. David Scholsser said in a news conference the man was found at about 1:30 a.m. in the Arlington National Cemetery, located near the Pentagon. He was first caught by the Ft. Myers police but then ran into adjacent Arlington National Cemetery, where he was apprehended by the military. When questioned, Melaku was uncooperative but then took the police to his car.
Melaku was arrested last month for smashing windows and stealing valuables from 27 cars in Leesburg, Va. He was charged with four counts of grand larceny although the police did not find any discernible ideological motive.
A man by the same name and birth month was also arrested in Fairfax County for reckless driving and failure to stop. He pleaded guilty and paid a $200 fine for the former charge and $30 for the second charge.
One of the Melakus' neighbors told reporters the young man's father worked as a taxi driver and that he was friendly but quiet.
"He's a pretty normal person," said Dagnachew Bizuwerk, an 11-year-old Ethiopian boy who lives across the street from Melaku's family. "He was a person that doesn't really talk a lot, a quiet man, doesn't say much."
ABC News' Howard Price, Lee Ferran, Steven Portnoy and Jake Tapper contributed to this report