A homemade device that remained for three weeks in a truck parked at the Government Printing Office had all the components necessary to detonate, an FBI explosives expert testified Monday.

Special Agent Daniel Hickey described the device at the trial of Michael Gorbey, who faces 14 charges, including the attempted manufacture of a weapon of mass destruction.

Those in “close proximity” to the device could have been “severely injured or possibly killed,” Hickey said. Though he stressed that it was hard to determine the actual distance of “close proximity,” he testified that a safe distance would be several hundred yards.

Capitol Police arrested Gorbey on Jan. 18, after seeing him walking near the Capitol, allegedly with a loaded shotgun. Later, investigators found the device in a Chevrolet pickup they believe Gorbey drove to Capitol Hill.

On Monday, Hickey described the pieces of the alleged bomb: explosive black powder, an old red tin can, firecrackers, shotgun shells, small metal spheres and a glass bottle.

Hickey only studied the bomb after a bomb squad “rendered it safe” — or blew it apart with water — but he testified that it appeared to be a “very crude anti-personnel device.” The tin can was filled with the black powder, he said, while the glass bottle was duct-taped to the outside. The shotgun shells and metal spheres may have been attached to the device as well.

Firecrackers found in the truck fit into a small hole in the can — meaning they could have served as the fuse, he said.

“It’s clearly designed to be an anti-personnel weapon,” Hickey said. “There’s no other reason to combine these components.”

During the cross examination, Gorbey and his assisting counsel, Eugene Ohm, emphasized the fact that Hickey never saw the device intact, except for photographs. Ohm paid special attention to the three components of an improvised explosive device: a charge, a container and a fusing system, the last of which he argued was not in place.

Hickey testified that he is uncertain whether there was a fusing system attached to the device, though he added that the red firecrackers found in the truck fit “very snugly” into the hole punctured into the can. Had the crude bomb exploded, Hickey testified, “it’s unlikely to create a series of events that would take down a building.”

Capitol Police didn’t find the device when they first searched the truck on Jan. 18. Declaring it safe, they stored it in a parking garage at the GPO headquarters on North Capitol Street. It was discovered in another search three weeks later.

Members have criticized the Capitol Police for not finding the device initially. Last week, the ranking member of the House Administration Subcommittee on Capitol Security, Rep. Dan Lungren (R-Calif.), indicated that the incident would be discussed in closed-door meetings.

Gorbey and Ohm filed a motion last week to suppress any testimony on what damage the device could have done if detonated, but it was dismissed by D.C. Superior Court Judge Gregory Jackson.

Alison McSherry contributed to this report.