In the nearly six months since a riotous mob descended on the U.S. Capitol intending to overturn a free and fair presidential election, federal authorities have racked up hundreds of arrests. But one arrest still eludes authorities half a year later: the person who set pipe bombs around Washington, D.C., the night before the attack.

It was the evening of Jan. 5 when an unidentified person wearing a backpack and a gray hooded sweatshirt placed two pipe bombs around the Capitol Hill area. The bombs, which contained an explosive black powder inside a steel pipe, were placed near the headquarters of the Democratic National Committee and behind the Republican National Committee headquarters.

The next day, after then-President Donald Trump told his supporters to fight like hell and the presidents personal attorney who was recently suspended from practicing law Rudy Giuliani said there may have to be a trial by combat, thousands of Trump supporters marched to the Capitol. Hundreds broke into the building, attacking law enforcement officers whom many rioters had claimed to support . Five people died in the violence, 140 law enforcement officers were wounded, and two officers died by suicide days after the riot.

If the goal was to overturn the election, Trumps mob ultimately failed. And now hundreds are reaping the consequences. In the six months since the attack, the FBI with the help of the public have arrested 500 people involved. Of those 500, 100 individuals have been arrested for assaulting federal law enforcement officers. But hundreds more identified by the FBI still remain at large, as does the would-be pipe bomber.

During a House Oversight Committee hearing in May, D.C. Metropolitan Police Chief Robert Contee said the suspect still remained at large.