March 9, 2021 8:00 PM EST

Every day since a violent mob rammed their way into the U.S. Capitol building on Jan. 6, the FBI has been tracking down and arresting suspects. More than 270 people allegedly involved in the deadly attack have been caught so far, with more than 300 facing federal charges.

One suspect, though, has managed to elude authorities: the person who planted pipe bombs the night before the insurrection outside the national offices of the Republican National Committee (RNC) and the Democratic National Committee (DNC). The two buildings are located a few blocks from the Capitol, and the undetonated bombs were found there Jan. 6.

On Tuesday, the FBI released new video footage that investigators say show the suspect prowling through the surrounding Washington neighborhood, wearing a gray hoodie, a face mask and carrying a backpack. Inside the bag, the FBI says, were threaded galvanized pipes, a kitchen timer and homemade black powder.

“These pipe bombs were viable devices that could have been detonated, resulting in injury or death,” Steven D’Antuono, the assistant director in charge of the FBI’s Washington field office, said in a statement on Tuesday. “We need the public’s help to identify the individual responsible for placing these pipe bombs, to ensure they will not harm themselves or anyone else.”

The new footage shows the suspect walking down the sidewalks in the Capitol Hill neighborhood at night. The individual holds the backpack at an arm’s length, like a sack of groceries, rather than over his or her shoulders. In one scene, the suspect stops to put down the backpack as a man walking a dog passes by, before picking it back up and stepping away again. Other scenes show the individual sitting down on a park bench, walking down an alley and even awkwardly waving under a street lamp as a D.C. police cruiser rolls by in the darkness.

The FBI says the suspect placed one bomb in an alley behind RNC headquarters and another next to a park bench near DNC headquarters on Jan. 5 between 7:30 p.m. and 8:30 p.m. local time. By posting the new video, authorities hope something will stick out to the American public about the suspect’s gait, mannerisms or clothing, which includes distinguishing footwear: black and gray Nike Air Max Speed Turf shoes with yellow details.

“We still believe there is someone out there who has information they may not have realized was significant until now,” D’Antuono said. “We know it can be a difficult decision to report information about family or friends—but this is about protecting human life.”

The FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) are offering a reward of up to $100,000 for information leading “to the location, arrest and conviction of the person(s) responsible.” D’Antuono says the government is grateful for the “invaluable assistance in this investigation” that tipsters have provided investigators. Anyone with information should call 1-800-CALL-FBI or submit online at tips.fbi.gov.

FBI Director Christopher Wray told lawmakers March 2 that the American public was the bureau’s “greatest partner” in the investigation, with more than 270,000 digital media tips about suspects in the Jan. 6 insurrection. The leads have come from a variety of sources, including friends, family and neighbors. One man, Richard Michetti, was charged with knowingly entering a restricted building, violent entry and disorderly conduct on Capitol grounds, and obstruction of Congress after his ex-girlfriend turned him in.

The number of federal cases against individuals involved in the Capitol Hill siege stands at 280, according to George Washington University’s ongoing analysis. Cases have been brought against 241 men and 38 women, who came from 40 states and the District of Columbia.

The mob stormed police lines, smashed windows and broke into the U.S. Capitol in an attempt to block lawmakers from certifying then-President-elect Joe Biden’s electoral victory. The violent scene, which called to mind images of coups in foreign lands, was a culmination of two months of “Stop the Steal” rallies, fueled by former President Donald Trump’s baseless allegations that widespread voter fraud had cost him the election. Trump repeatedly incited his supporters to challenge the peaceful transfer of power, the essential marker of democracy. When the smoke cleared and the siege ended, there were five people dead, including a U.S. Capitol Police officer.

An independent 15-page draft report, which reviewed security at the U.S. Capitol, found that Capitol Police lacked in intelligence-gathering capabilities to protect Congress from attack. The report, which was commissioned by House Speaker Nancy Pelosi, was led by retired Army Lt. Gen Russel Honoré and outlined that law enforcement was “understaffed, insufficiently equipped and inadequately trained” to handle such a mob.

Insurrectionists openly planned to storm the Capitol on social media. The U.S. Capitol Police, which has a force of about 2,000 officers, along with city authorities, had been aware of the pro-Trump rally for weeks. And then-Capitol Police Chief Steven Sund, said in a statement on Jan. 7 that officers had had a “robust plan” to deal with expected unrest.

Despite meticulous training and contingency plans for a host of scenarios from terrorist attacks to biohazards, the Capitol Police seemed unprepared when the threat arrived in the form of mostly white men carrying American flags.

Write to W.J. Hennigan at william.hennigan@time.com.

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