Washington — The individual who investigators say left two pipe bombs outside the headquarters of the Democratic and Republican parties in Washington, D.C., the night before the Jan. 6, 2021, Capitol attack is still on the loose, and the FBI is offering a $500,000 reward for information that leads to the arrest of the person responsible. 

The unsolved mystery continues to elude investigators three years later, even amid a public campaign providing detailed maps, security camera video and potentially identifying information. Investigators made public over two years ago footage showing the suspect walking through the Capitol Hill neighborhood around the time that the devices were believed to have been placed and published photos of the devices and photos and descriptions of some of the apparel the person was wearing. 

The FBI says that the unknown individual wore Nike Air Max Speed turf shoes, a face mask, glasses and gloves and a gray hooded sweatshirt.

The pipe bombs did not detonate, but the FBI has said they were "viable" and posed a danger to the public. 

Around 1 p.m. on Jan. 6, as Capitol rioters began to breach police barricades around the outer perimeter of the U.S. Capitol, authorities said, the two pipe bombs were found by a passerby at the DNC and RNC headquarters. Both of the buildings are just a couple of blocks from the Capitol.

Vice President Kamala Harris, who was the vice president-elect at the time, was evacuated from the Democratic National Committee headquarters when the devices were recovered. According to a U.S. Capitol Police timeline obtained by CBS News, the U.S. Secret Service and Capitol Police evacuated a "protectee" at DNC headquarters at 1:14 p.m., minutes after the pipe bomb was discovered at 1:07 p.m.

The FBI said the bombs were placed outside the RNC and DNC the night before the attack, between 7:30 p.m. and 8:30 p.m., and according to a report obtained by CBS News in March 2021, the bombs contained only one method of detonation — a 60-minute kitchen timer. The report — which was written by the National Explosives Task Force, a multi-agency group that coordinates explosive expertise for law enforcement and intelligence agencies — suggested there was no evidence of a second or remote detonation method, such as a cellphone. 

It remains unclear why the pipe bombs did not detonate or if they were meant to at all, but law enforcement sources told CBS News at the time that the devices could have been designed to explode the day before the electoral college certification at the Capitol. 

"Three years into the investigation, identifying the perpetrator of this attempted attack remains a priority for the FBI, ATF, MPD, and the USCP," the FBI said in a statement this week. The head of the Bureau's Washington, D.C. field office said a team of agents and scientists have logged thousands of hours working on the case. 

In an interview with congressional investigators last year, Steven D'Antuono, the former special agent in charge of the FBI's Washington field division said investigators had conducted a near "complete geofence" of the area in question using cellphone data and had numerous agents assigned the case. 

"When I was there for 2 years it was a high priority, as much detail as they want, we put every resource that we could. We did every check, every lab test, every data. We ran this through systems back and forth, up and down, sideways, all over the place," D'Antuono said, according to a transcript of the closed-door interview. 

–Tim Perry, Michael Kaplan and Nicole Sganga contributed reporting. 

In:
• January 6
• Washington
• Capitol Hill

Robert Legare is a CBS News multiplatform reporter and producer covering the Justice Department, federal courts and investigations. He was previously an associate producer for the "CBS Evening News with Norah O'Donnell."