A jury found Ibrahim Suleiman Adnan Adam Harun, known by the nom de guerre Spin Ghul, guilty of all counts after only two hours of deliberations. He faces life in prison at his sentencing.
Harun was not present in court for the trial. Since his extradition from Italy in October 2012, he has insisted he is a "warrior" who should face a military tribunal rather than criminal proceedings.
Before one court appearance in May, Harun struggled with US marshals and ripped off his clothes in an effort to avoid coming to court. US District Judge Brian Cogan has allowed Harun to observe the proceedings from a jail cell.
As of the start of his trial 10 days ago, Harun had not spoken with his court-appointed defence lawyers for two years.
Prosecutors used Harun's own words against him during the trial, playing recordings taken in Italy after his capture in which he described how he dreamed of joining "jihad" as a young boy.
"The defendant embraced terrorism at a young age and made it his life's work," Assistant US Attorney Matt Jacobs said in his opening statement.
Harun, who claims Niger citizenship, travelled to Afghanistan to join al Qaeda weeks before the attacks of Sept. 11, 2001, on US soil, prosecutors said.
After receiving extensive arms training, Harun fled with other fighters to the mountainous region along the Pakistan border.
In 2003, he took part in an assault on US troops in 2003 that killed Army Private 1st Class Jerod Dennis, 19, and Air Force Airman 1st Class Raymond Losano, 24, prosecutors said. A Koran recovered from the site bore Harun's fingerprints.
Eventually, Harun made his way to Nigeria, where he planned to bomb the U.S. embassy before he was captured in Libya in 2005.
He was released onto a refugee ship in 2011 and taken into custody by Italian authorities after he acknowledged his battle scars were the result of fighting for al Qaeda against American soldiers.
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