Chattanooga, Tennessee (CNN)A once devoted, disciplined mixed-martial-arts fighter. A top student known for smarts, charm and humor. A devout Muslim, who kept in touch with his roots in the Middle East.
That's how a former coach and classmates describe Mohammad Youssuf Abdulazeez, 24, who killed four U.S. Marines and wounded three more people Thursday in Chattanooga. Police killed Abdulazeez.
People who knew him were stunned to hear he was the man who sprayed a military recruiting center at a strip mall with bullets, then drove seven miles to assault Navy Operational Support Center Chattanooga.
The FBI hasn't released much information on Abdulazeez, saying it doesn't yet know what motivated the bloodshed but it is working on an assumption. "We will treat this as a terrorism investigation until it can be determined that it is not," FBI Special Agent Edward Reinhold said.
'National security alerts' joke
Abdulazeez was born in Kuwait in September 1990, during the Iraqi invasion of that country, Kuwait's Interior Ministry said Friday. The ministry didn't explain how Abdulazeez came to be born there but said he holds Jordanian citizenship.
Jordanian sources, however, denied that he was a Jordanian citizen, but rather a Palestinian who carried a Jordanian travel document. The sources said he was born Mohammad Youssuf Saeed Hajj Ali on September 5, 1990, but that his father changed his name that year to Abdulazeez.
U.S. law enforcement officials said he was a naturalized U.S. citizen.
His former coach in mixed martial arts, Scott Schraeder, thought of him as "all-American."
"There were tears in my eyes," Schraeder said of the moment he heard the news. "He was one of the nicest kids we trained."
Former 10th-grade classmate Kagan Wagner, who now lives in Washington state, said Abdulazeez "always fit in."
"He had a big group of friends. He was never bullied or treated like an outcast. He was pretty popular," Wagner told CNN's Drew Griffin.
And he was funny, she said. "Always had a witty comment to add."
Next to his senior yearbook photo from 2008, Abdulazeez added a quip he attributed to "Hijabman." "My name causes national security alerts. What does yours do?" it said.
Wagner said she believes he was making a joke, and never thought he could do anything like what happened in Chattanooga.
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"It was funny at the time," she said, "and now, it's a little morbidly ironic."
The two classmates lost touch after graduation. Abdulazeez went to the University of Tennessee at Chattanooga, where he graduated with a degree in electrical engineering in 2012.
Called in sick at work
Abdulazeez worked at the Franklin, Tennessee, location of wire and cable manufacturing firm Superior Essex Inc., the company confirmed Friday in a letter distributed to employees.
He had worked there for three months, the company said, without offering any details about what he did or how he performed.
CNN affiliate WKRN-TV, citing an unnamed Superior Essex employee, reported Abdulazeez had called in sick Monday and Tuesday and was scheduled to be off Wednesday and Thursday.
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Devout but not 'overly religious'
People who knew Abdulazeez described him as religious.
"He was a devout Muslim and used to talk about his families' prayer habits, and that always interested me to hear about his culture," said Samantha Barnette, another former classmate.
He at times interrupted training sessions with fighting coach Schraeder to pray.
"I wouldn't call it overly religious," Schraeder said. "He followed his religion; he would pray at 6 o'clock. He'd go into our office and pray." But he would skip prayers at times, he said.
Schraeder said he does not believe Abdulazeez was an extremist.
"His favorite training partner to grapple with -- not striking, but actually submission grapple with, when you're actually on the ground in close proximity contact with -- was a Russian Jew, hardly what you would see as someone who would be a radical Islamist," Schraeder said.
Return to Middle East
Abdulazeez also once trained as a fighter under coach Almir Dizdarevic. They also knew each other from mosques they attended, even after the training relationship ended. They would bump into each other and chat, or Dizdarevic would speak with his family.
He had heard his former athlete moved to the Middle East a year or so ago.
"He went back home and he stayed overseas," Dizdarevic said. "And I asked his dad about, you know, where's Mohammad? I haven't seen him in a while, and he said, 'He moved back home.'"
Jordanian sources said Abdulazeez had been in Jordan as recently as 2014 visiting an uncle. He had also visited Kuwait and Jordan in 2010, Kuwait's Interior Ministry said.
Dizdarevic and Abdulazeez saw each other occasionally when the latter visited. "I asked him 'How is everything, what you doing?' He said he is teaching kids, he is teaching wrestling," Dizdarevic said.
Then Abdulazeez moved back to Tennessee.
The last time the two greeted each other was a month ago after Friday prayers, Dizdarevic said. It seemed like everything was fine.
Then Dizdarevic heard the news about his former trainee on Thursday.
"When they actually showed a picture on the news, I mean I looked at the phone, and I was like, 'Wow, I can't believe this,' " he said. Dizdarevic said he had been a police officer himself but resigned. He has talked to his former colleagues about anything he knew about Abdulazeez.
He can't believe Abdulazeez was radicalized through anyone in Chattanooga. Any extremism influence would have had to come from somewhere else, he said.
Investigators are examining a blog authored by a user designated as "myabdulazeez," but they have not confirmed that it belonged to the gunman.
Only two posts appear on it, both dated three days before the shooting. One compares life on Earth with being in a pleasant prison. The other encourages readers to follow historic Islamic figures, who the writer said fought in jihadi wars.
Not in databases
Abdulazeez was not in any U.S. databases of suspected terrorists, a U.S. official said.
His only reported prior trouble with the law was a DUI arrest in April. His court hearing was scheduled for July 30.
A police officer stopped Abdulazeez for failing to maintain his lane, driving slowly and stopping at green lights. According to a police affidavit, the officer "noticed an odor commonly associated with an alcoholic beverage and the odor of burnt marijuana" coming from Abdulazeez.
He was unsteady, with droopy eyelids and slurred speech, and had a white powdery residue under his nose, police wrote, adding that Abdulazeez said the white substance was crushed caffeine pills.
When he killed the four Marines, Abdulazeez was carrying an AK-47-style rifle and a lot of ammunition, a law enforcement official said.
He held off responding police officers for a while, an official said. Police found 30-round magazines on his body and several weapons, said Reinhold, the FBI special agent.
Abdulazeez appeared to have acted alone.