NEW YORK — To US prosecutors, Osama bin Laden’s son-in-law was his trusted, right-hand man who conspired to kill Americans and inspired a new generation of Al-Qaeda terrorists after the 9/11 attacks.

In words of the defense, Sulaiman Abu Ghaith was never a terrorist but a respected imam. His views might sicken the jury, but he never conspired to kill anyone.

On Tuesday a New York jury will begin deliberations on whether Abu Ghaith is guilty of conspiracy to kill Americans and of conspiring and supporting terrorists.

The highest-profile Al-Qaeda trial yet in a US federal court, the outcome will be closely watched as pressure builds on the White House to close Guantanamo Bay.

The 48-year-old preacher from Kuwait denies the charges. He faces life in prison if convicted.

In follow-up videos he threatened America with a “storm of airplanes” — proof the government says that he was implicated in the December 2001 plot to blow up a transatlantic flight from Paris with a shoe bomb.

In this undated photo, Sulaiman Abu Ghaith, left, gestures toward al-Qaeda founder Osama Bin Laden, somewhere in Afghanistan (photo credit: AP/US Attorney’s Office for the Southern District of New York)

In this undated photo, Sulaiman Abu Ghaith, left, gestures toward al-Qaeda founder Osama Bin Laden, somewhere in Afghanistan (photo credit: AP/US Attorney’s Office for the Southern District of New York)

The prosecution urged the jury to find the defendant guilty on all three counts, referring repeatedly to what they called “overwhelming” evidence against him.

Video and audio clips, his confession to an FBI agent en route to the United States last year and his testimony on the stand all proved his guilt, they said.

‘An Al-Qaeda insider’

Assistant US attorney John Cronan presented him as an Al-Qaeda insider, hired by bin Laden to take his propaganda global as the Twin Towers lay smouldering.

“Just hours after four planes came crashing into our country… in the utter chaos of that terrible day, Osama bin Laden turned to this man,” he thundered, standing over the suited defendant.

“In the most important period of time in Al-Qaeda’s savage history Suleiman Abu Ghaith was Osama bin Laden’s principle messenger,” he said.

“This man was not Osama bin Laden’s robot. He was not Osama bin Laden’s puppet,” said Cronan.

The two men shared mutual respect and admiration, calling each other sheikh. He was a “trusted confidant and co-conspirator of Osama bin Laden,” he said.

In 2001 and 2002 Abu Ghaith sat at bin Laden’s right hand, justifying the mass murder of Americans and recruiting the next generation of terrorists, he said.

It was an emotive speech, repeatedly invoking the 9/11 attacks in a courtroom within sight of where the Twin Towers were reduced to smouldering rubble.

“Al-Qaeda is about murdering Americans and regardless of role, participating in that conspiracy in any way whatsoever is a crime. Did that man knowingly participate in that conspiracy? Of course he did.”

‘No drop of evidence’

Defense attorney Stanley Cohen tore into the government’s witnesses: law enforcement officials who never once came across Abu Ghaith, two convicted terrorists who lied and plotted mass murder, and an expert who contradicted himself on the stand and tweaked reports in compliance with government requests.

“There just aint a drop of evidence” connecting Abu Ghaith to the shoe bomb plot, said Cohen, dismissing any such link as “outrageous speculation”.

Stanley L. Cohen, a lawyer representing Osama Bin Laden's son-in-law, Sulaiman Abu Ghaith, speaks to reporters outside federal court in New York City on March 24, 2014 (photo credit: Andrew Burton/Getty Images/AFP)

Stanley L. Cohen, a lawyer representing Osama Bin Laden’s son-in-law, Sulaiman Abu Ghaith, speaks to reporters outside federal court in New York City on March 24, 2014 (photo credit: Andrew Burton/Getty Images/AFP)

He presented his client as a pious man who got a degree, became an imam, a teacher and an administrator who “had no problem” with the Americans who liberated his country after the 1990 Iraqi invasion.

He painted Abu Ghaith’s move with his family to Afghanistan in 2001 as “a young middle life crisis” by a man attracted to an Islamic state ruled by sharia law where he could “help people in need”.

His speeches were not about terrorism, jihad or killing Americans, but about history, tradition and sharia, Cohen said, albeit alluding to anti-American sentiment pervasive in the Middle East and Afghanistan.

“Some of his associations may sicken you… but that does not establish a conspiracy to murder Americans.”

“Look beyond the horrors of 9/11 and do what your oath says you must do,” he said.

“This man, this human being is not guilty on all counts,” Cohen added.

Abu Ghaith, who fled Afghanistan for Iran in 2002, was arrested in Turkey in 2013 and sent to Jordan, where he was handed over to US custody.