Something happened to Mohammod Youssuf Abdulazeez after he traveled to the Middle East to spend time there, according to several credible reports.
"He never became close to me like he was before he went overseas. ... I'm sure he had something that happened to him overseas," said Abdulrazzak Brizada, who described himself to CNN as a friend.
Reuters has reported that hours before the Chattanooga gunman attacked two military installations, he texted a friend a link to an Islamic verse that included the line: "Whosoever shows enmity to a friend of mine, then I have declared war against him."
Reuters did not identity the name of the friend because he requested anonymity. The friend told the international news agency, which operates in a similar fashion to the Associated Press, that the shooter returned from a trip to Jordan in 2014 and bought three assault rifles.
CNN has also reported that the shooter had several guns, and would go shooting as a hobby. The news agency has reported that police seized four guns.
"He expressed that he was upset about (the Middle East). But I can't imagine it drove him to this," said the friend who received the text message, according to Reuters.
Abdulazeez's trip to Jordan has become a focal point of the investigation into why the devout 24-year-old chose to open fire on Marines, sailors and police officers in Chattanooga on Thursday. He also traveled to Kuwait and Jordan in 2010.
Other friends told Reuters that Abdulazeez was upset about Israel's bombing of Gaza, and the civil war in Syria. One of his friends, who Reuters said asked not to be identified for fear of a backlash, said Abdulazeez was upset about the effect of U.S. influence in the region.
A blog that the SITE Intelligence Group said was penned by Abdulazeez muses upon the role of Sahaba, the companions of the prophet Muhammad, who he said all 'fought Jihad for the sake of Allah."
"Every one of them had to make sacrifices in their lives," the blog's author wrote. "
The group did not reveal how it was able to link the blog to Abdulazeez, but confirmed to the Times Free Press that it believed the blog was genuine.
In another post on the same blog, he wrote that life is "short and bitter."
Read more about the attacks on Chattanooga military facilities