Suleiman Abu Ghaith (file)
Suleiman Abu Ghaith (file)Reuters

Sulaiman Abu Ghaith, 48, former Al Qaeda spokesman and Osama bin Laden’s son-in-law, was found guilty Wednesday in a New York City courtroom of conspiring to kill Americans, conspiring to provide material support to terrorists and providing support to terrorists.

The jury returned its unanimous verdict after about five hours of deliberation.

In the months after the attacks of September 11, 2001, Abu Ghaith encouraged young Muslims to kill Americans in several video and audio broadcasts, which were played repeatedly throughout the trial. In his own testimony, he denied being a member of Al Qaeda, but also testified that Bin Laden had asked him to be the group's spokesman on the night of the 9/11 attacks. He said that Bin Laden met him in a cave and asked him: "Did you learn what happened? We are the ones who did it."

Videos showing Abu Ghaith threatening America with no end to the "storm of airplanes'' were shown to jurors, but he argued his role was a purely religious one.

George Venizelos of the FBI, who works on the Joint Terrorism Task Force, compared Abu Ghaith’s role in Al Qaeda with that of a mafia consigliere.

On Monday, during closing arguments, Assistant US Attorney John Cronan said Abu Ghaith was an important figure in post-9/11 Al Qaeda.

"Going to that man was the very first thing Osama Bin Laden did on September 11 after the terror attacks," he said. "The defendant committed himself to Al Qaeda's conspiracy to kill Americans, and he worked to drive other people to that conspiracy."

Abu Ghaith's defense lawyers argued there was "zero evidence" that he knew about any conspiracies and that the prosecution case was based purely on "ugly words and bad associations."

 Abu Ghaith was captured in Jordan last year and brought to the US, where he was tried in a Federal civilian court. The trial took only three weeks, and is seen by some as proof that civilian trials are a more efficient means of bringing terrorists to justice than military trials.

Abu Ghaith will be sentenced on September 8th and could face life in prison. The Kuwaiti citizen is the highest-ranking Al Qaeda figure to face trial on US soil since the attacks.

His trial saw new revelations come to light about the world's most notorious terrorist group, as former British Al Qaeda terrorist Saajid Badat agreed to testify against Abu Gaith.