Authorities are in search of the pipe bomber who planted explosives near the U.S. Capitol on the night before the insurrection.

According to FBI agents, two eight-inch long pipe bombs were planted near the Democratic and Republican party headquarters between 7:30 and 8:30 p.m. on Jan. 5 — the night before the riots. They were discovered the following day (Jan. 6), as pro-Trump rioters stormed the government building. The first one was found by a 36-year-old woman on her way home from doing laundry; the second was located within the next 30 minutes. Both bombs were rigged to egg timers and filled with an explosive powder, but safely detonated by robots shortly after officers responded to the scene.

Investigators are trying to determine why the pipe bombs — which were exposed — failed to explode. They believe the bombs — which were either timed incorrectly or set with expired batteries — may have been planted as a ploy to lure cops away from the Capitol so rioters could raid the building freely.

As an examination of the explosive devices continue, photos have been released of a possible suspect, who is wearing Nike Air Max Speed Turf shoes in yellow, a gray hooded sweatshirt, a facemask and a backpack. Authorities are offering $100,000 in reward money for information that leads them to the arrest ot the pipe bomber, who they believe could still be planting explosives.

The FBI has successfully detained over 100 rioters for their participation in the Jan. 6 siege, including a few Capitol officers who are now facing investigations and the Hughes brothers who accosted Officer Eugune Goodman near the Senate chambers. The government agency is reportedly contemplating whether they should also pursue criminal charges against the participants who entered the building but didn’t contribute to the chaos.