CNN  — 

Two pipe bombs near the Democratic and Republican party headquarters discovered on January 6 were planted the night before the insurrection at the Capitol, the FBI said Friday.

Federal authorities again increased the reward for information about the pipe bomber and released new details and photos of a suspect on Friday, underscoring the urgency the Justice Department is treating this angle of the investigation, which remains one of the most troubling mysteries for law enforcement.

A new wanted poster says the bombs were placed between 7:30 and 8:30 p.m. on January 5, the night before the insurrection.

The FBI also identified the suspect’s shoes as Nike Air Max Speed Turf shoes in yellow, black, and gray, and included enhanced photos of them, along with photos of the devices.

The reward for information leading to the location, arrest, and conviction of the person or people responsible for placing the bomb is now $100,000. The FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives had already increased the reward once – to $75,000 – earlier this month.

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CNN was first to report Wednesday that the bombs were eight inches long and made of galvanized steel, according to a law enforcement official. They had been rigged to egg timers and filled with an explosive powder, the official said. Investigators have been scrutinizing the remains of the devices at the FBI lab in Virginia and urging the public to submit information, concerned that the bomber could still be at work.

The bombs were discovered within minutes of each other around 1 p.m. ET on January 6, just around the time that a mob of angry supporters of President Donald Trump descended on the building after a nearby rally with the President, according to an account the acting chief of the US Capitol gave to lawmakers Tuesday and the FBI poster.

Officers from the ATF, FBI, US Capitol Police and DC Metropolitan Police had responded to the scene at the two offices, which are less than a quarter mile apart and just blocks south of the Capitol, and the bombs were safely detonated at the scene by robots.

Investigators are considering the possibility that the devices were part of a plan to divert law enforcement resources away from the Capitol as rioters began to force their way in. The devices were placed out in the open.

One, by the offices of the Republican National Committee, was discovered by a 36-year-old on her way back from putting in a load of laundry.

“I just happened to look down by sheer luck,” Karlin Younger told the Wisconsin State Journal. “And I noticed that by the recycling bin there was this tangle of wires.”

It’s still unknown why the devices did not explode, the law enforcement official told CNN earlier this week. One theory under investigation is that the timers were set incorrectly. Another is that the batteries may have been improperly connected, the official said.

A photo of the person believed to have planted the bombs, taken from surveillance images, has been widely shared by law enforcement.

In the photos, the person appears in a gray hooded sweatshirt and is carrying a backpack.

This story has been updated with additional information.