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In the year since a deadly riot threatened to overturn democracy, hundreds of supporters of former President Donald Trump have been arrested and charged with crimes related to the breach of the U.S. Capitol on Jan. 6. A House committee is currently probing how the violence was organized, and Trump himself is feeling the intense pressure of its inquiries. But one dark mystery lingers: Who planted two potentially lethal pipe bombs in key locations around Washington, D.C., the night before the attack?

Its a question the FBI has been asking for the past year, but so far at least publicly has not found the answer to.

A 20-Minute Timer

The first pipe bomb was found by sheer luck. It was the afternoon of Jan. 6, just hours before thousands of Trump supporters would swarm the Capitol and hundreds more would breach its doors. Karlin Younger, a D.C. resident, was holding a wine-stained sweater outside of her laundry room when she noticed a metal object by the trash can outside the Republican National Headquarters.

Youre just staring at it, and youre like, Okay, its definitely metal, Younger told Insider in October . But theres like wires attached to it, and theres a timer attached to it. What am I looking at? Its not immediately obvious because youre just really, really not expecting anything.