Authorities in the United States have arrested a suspect they say was involved in leaving pipe bombs near the headquarters of the country’s two major political parties in Washington, DC, during the night before the Capitol riot on January 6, 2021.

The Federal Bureau of Investigation (FBI) and the Department of Justice identified the suspect on Thursday as Brian Cole Jr from Virginia.

The arrest potentially ends a nearly five-year-long mystery that underscored the rising threat of political violence in the US.

Law enforcement agencies have said that the bombs, which did not explode, were viable and “could have seriously injured or killed innocent bystanders”.

Officials offered $500,000 for information on the perpetrator, warning that the suspect “may still pose a danger to the public”.

Early on, authorities released grainy footage of the person who left the bombs. The suspect, long believed to be a man, was captured on surveillance cameras wearing a mask, gloves and a grey hoodie.

The perpetrator walked through the densely populated Capitol Hill neighbourhood to arrive near the offices of the Democratic and Republican Parties, where he placed the pipe bombs.

Last year, the FBI said its analysts, agents and law enforcement partners had “worked thousands of hours conducting interviews, reviewing physical and digital evidence, and assessing tips from the public about who may have placed pipe bombs on Capitol Hill”.

The day after the bombs were left, President Donald Trump’s supporters stormed and ransacked the US Capitol to prevent the certification of Joe Biden’s victory in the 2020 elections.

Trump continues to falsely claim that his election loss that year was due to widespread voter fraud.

In one of his first decrees after returning to the White House early in 2025, Trump issued a presidential pardon for more than 1,500 people charged or convicted of criminal offences related to the riot.

The mystery surrounding the pipe bombs has fuelled right-wing conspiracy theories that the Capitol riot was an “inside job”. Some online personalities have maintained, without evidence, that the would-be bomber was a “deep state” government agent who sought to discredit Trump’s supporters.

But even some Trump officials who previously helped spread such theories, like Dan Bongino, have since come out strongly against them.

Last month, Bongino, now the second-in-command at the FBI, denounced rumours about the pipe bombing case, calling them “grossly inaccurate”. He added that the misinformation “serves only to mislead the public”.