vehicle operator with the 4th Combat Engineer Battalion, headquartered in Baltimore, and has not been deployed overseas. He has received the National Defense Service Medal and the Selected Marine Corps Reserve Medal.

The Washington Post is reporting that Melaku was arrested early May 26 after more than 25 cars in Leesburg, Va., were vandalized. AP says he was charged with four counts of grand larceny.

By Douglas Stanglin

USA TODAY

Update at 12:18 p.m. ET: CBS News investigative producer Pat Milon, quoting unnamed sources, reports that the person who was detained has been identified as Lance Cpl. Yonathan Melaku, a member of the U.S. Marine Corps Reserve.

Update at 10:55 a.m. ET: The Associated Press quotes a law enforcement official, speaking on the condition of anonymity, as saying officials found what appeared tobe a small quantity of ammonium nitrate in the suspect's backpack, but there was nothing that would have enabled an explosion. The official, the AP reports, says tests are being done to determine the exact concentration.

Update at 9:52 a.m. ET: U.S. Park Police detained a man early today who was found in Arlington National Cemetery near the Pentagon with a backpack containing suspicious materials.

FBI Agent Brenda Heck says the man, whose identity was not released, remains in custody. She says that despite earlier reports, there was only one individual involved in the incident.

Heck would not divulge the material found in bags in the suspect's backpack but says it was found to be "inert."

She would not comment on reports from ABC News that ammonia nitrate, spent 9mm shells and