Yonathan Melaku was sneaking through Fort Myer and Arlington National Cemetery, his backpack filled with plastic bags of ammonium nitrate, a notebook containing jihadist messages, and a can of black spray paint. The 23-year-old former Marine was heading to the graves of the nation's most recent heroes, aiming to desecrate the stones with Arabic statements and leave handfuls of explosive material nearby as a message. Before police foiled the plan in June, the vandalism was to be Melaku's sixth attack, months after he went on a mysterious shooting spree that targeted the Pentagon, the National Museum of the Marine Corps and two other military buildings in Northern Virginia. A video found after Melaku's arrest showed him wearing a black mask and shooting a 9mm handgun out of his Acura's passenger window as he drove along Interstate 95, shouting "Allahu Akbar!"