The components that could be used to make a pipe bomb were discovered behind the passenger seat on Feb. 8 — three weeks after Michael Gorbey was taken into custody, a source told The Hill.

Senate Sergeant at Arms Terrance Gainer confirmed Monday that Capitol Police found “hazardous material” in the green Chevrolet pickup that Gorbey drove shortly before he was arrested on Jan. 18.

The truck was stored in one of the storage facilities on Capitol Hill while police obtained a search warrant, Gainer said.

"It's not uncommon in cases like this for a specialized unit to neutralize the threat and then obtain a search warrant for further investigation," said Gainer, who is also a former Capitol Police chief.

Gorbey, 38, was arrested for carrying a loaded shotgun near the Supreme Court.

A Capitol Police bomb squad used a robotic water cannon to disrupt the contents of the truck, checking for possible explosives on Jan. 18. They found several propane tanks but determined that the parked vehicle posed no explosive danger. The criminal investigative unit then took possession of the vehicle.

Authorities received a search warrant and probed the truck further, on Feb. 8 finding the makings of an explosive device hidden beneath a towel behind the passenger seat of the truck, according to a source, who added that there was not an intact detonator and that the bomb could not therefore be activated.

A potential pipe bomb in a vehicle driven by a convicted felon apprehended with a loaded shotgun is certain to bring to mind the last deadly shooting on Capitol Hill.

In 1998 two Capitol Police officers, Detective John Gibson and Pvt. 1st Class Jacob Chestnut, were killed by Russell Weston Jr. as he attempted to enter the Capitol building with a handgun.

Gorbey has a lengthy criminal record dating back to 1991, including several felony convictions and a previous conviction for the crime he is currently being charged with — felon in possession of a firearm.

In an interview at Washington, D.C., Central Detention Center, Gorbey told The Hill on Jan. 29 that he was arrested on his way to a scheduled meeting with Chief Justice John Roberts, an appointment that he had set up through the clerk’s office of the court. He denied having the shotgun and accused police of manufacturing evidence.

Kathy Arberg, spokeswoman for the Supreme Court, said on Jan. 29 that they had no record of such an appointment and that it is “very rare” for a member of the general public to be able to schedule one.

Last week Gorbey appeared in D.C. Superior Court and told Judge Gregory Jackson that he wished to represent himself.

In 2005, he represented himself in U.S. District Court for the Northern District of West Virginia against the same charge of a felon in possession of a firearm. The jury found him not guilty.

Gorbey, of Rapidan, Va., told The Hill that in the backpack he was carrying on the day he was arrested were shells of bullets that he said were fired at him by police officers in Virginia and West Virginia, while he was living in national parks with his girlfriend and two children, ages 4 and 8.

Gorbey, who has expressed his desire to represent himself, is currently a client of the Washington, D.C. public defender’s office and is due to appear in court on Feb. 14.