Sulaiman Abu Ghaith, Osama bin Laden's son-in-law, was sentenced to a life-term in prison in the U.S. Tuesday, for ties to terrorist groups that aimed to kill Americans, Reuters reported.

Jerika Richardson, a spokeswoman for the U.S. Attorney's Office in Manhattan, said Abu Ghaith, 48, was found guilty in March of helping al-Qaida terrorists conspire to kill Americans and providing material support to terrorists.

"Justice has been served," U.S. Attorney General Eric Holder said in a statement, according to CNN. "This outcome ensures that Sulaiman Abu (Ghaith), a senior member of al-Qaida and an associate of Osama bin Laden, will never again set foot outside a prison cell."

Abu Ghaith, a Kuwaiti cleric, was flown to the U.S. a year ago from Jordan and charged with conspiring to kill Americans, but the U.S. government never alleged he was directly involved in carrying out the 9/11 attacks, CNN reported.

He was said to be a propagandist for al-Qaida, and had been pushing for recruits after 9/11.

"He was more than just Osama bin Laden's propaganda minister. Within hours after the devastating 9/11 attacks, Abu Ghayth was using his position in al-Qaida's homicidal hierarchy to persuade others to pledge themselves to al-Qaida in the cause of murdering more Americans," Manhattan U.S. Attorney Preet Bharara said in a statement, CNN reported.

He served as a confidant for the leaders in al-Qaida and was persuasive in turning Muslims into radical jihadists.

Abu Ghaith said he was never a part of the terrorist ring and did not know that 9/11 was going to occur before it happened. He had only met bin Laden in June of that year, he said, and only assisted bin Laden on spiritual topics.

There was initially a debate over where to set the fair trial for Abu Ghaith, with one option being Guantanamo Bay in Cuba, but the final decision set the court in Manhattan, a few blocks away from the World Trade Center site, and family members of the victims attended the trial.