Some 30 police officers raided the Aurora building, which houses the offices of a Roma activism center and an agency aiding refugees, and detained 15 people they said were in possession of cannabis.
Matthew Kuppe, 22, was taken into federal custody a day after he had been scheduled to enter prison and two days after he was found "unresponsive" in his home and taken to a hospital.
Federal prosecutors say Juan Thompson's threats were copycat crimes during a wave of nearly 150 bomb threats to Jewish institutions during the first three months of this year.