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Mohammad Youssef Abdulazeez, the gunman who allegedly killed four Marines and a Navy sailor last week in Tennessee, had downloaded audio recordings of Anwar al-Awlaki, the American-Yemeni cleric who was a recruiter for al Qaeda, law enforcement officials told NBC News.

The gunman also had CDs of al-Awlaki's sermons, the officials said. Al-Awlaki was killed by an American drone strike in Yemen in 2011.

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A law enforcement official also told NBC News that Abdulazeez's uncle in Jordan is believed to be "radical" and officials are investigating whether he influenced Abdulazeez when he was living there. Abdulazeez traveled to Jordan from April to November 2014.

Abdulazeez's family said Tuesday that the uncle is not radical as was described. They said the uncle, 40, is a naturalized U.S. citizen born in Kuwait, and is a business owner in Jordan who moved to that country in 2010 to help take care of his parents.

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The uncle has been detained in Jordan since the day after the attack, a lawyer there told The Associated Press. Computers and phones were taken from the man's home, but he has not been charged, the lawyer said.

Investigators are trying to determine the motive behind the deadly rampage. Abdulazeez, 24, was killed in a shootout with police during the attack on a reserve center. Abdulazeez's family said he had been depressed for years.

The law enforcement officials told NBC News that investigators are looking into whether at least two acquaintances in Tennessee knew of Abdulazeez's plans in the months before the attack.

Investigators in Chattanooga, the officials said, are also trying to determine whether two acquaintances who went with Abdulazeez to buy ammunition were aware of his plans.