The family has issued a statement, we are told, that their son was depressed. http://www.cnn.com/2015/07/19/us/tennessee-naval-reserve-shooting/
And his friend says he was upset about Gaza. http://www.i24news.tv/en/news/international/americas/78886-150719-tennessee-attack-gunman-upset-about-2014-gaza-war
Now this revelation from Walid Shoebat. I think we are only beginning to learn about what the motive was.
"Something happened over there," Abdulrazzak Brizada said. "He never became close to me like he was before he went overseas. ... I'm sure he had something that happened to him overseas.
The investigators will probably find their answers in the Middle East. He spent several months over there and they need to learn where he spent his time and with whom.
Muslim families in the US send their sons to their homeland when they reach a certain age in order to have them find their roots.