The FBI has arrested a man accused of placing two pipe bombs outside the headquarters of the Republican and Democratic national parties in Washington on the eve of the U.S. Capitol attack. It's an abrupt breakthrough in an investigation that for years flummoxed law enforcement and spawned conspiracy theories about Jan. 6, 2021. The suspect has been identified as 30-year-old Brian J. Cole Jr. of Woodbridge, Virginia. Key questions remain unanswered after his arrest on explosives charges, including a possible motive and what connection if any the act had to the assault on the Capitol the following day by supporters of President Donald Trump.