The FBI is not calling Mohammad Youssef Abdulazeez a terrorist — not yet, at least.

Officials, for now, are labeling him something else. The words used at a news conference Wednesday were more nuanced.

"He is being treated as a homegrown violent extremist," said FBI Special Agent Ed Reinhold.

Terrorists, by definition, are killers with an ideological agenda, experts say. They intend for their violence to send shock waves, to strike fear and influence policy.

Yet, so much is still unknown about Abdulazeez's intent, although it is clear his faith played a significant role in his decision to arm himself, fire into a military recruitment center and then ram into a military base and kill five service members.

On Wednesday, investigators skirted all questions about motive. Reinhold wouldn't answer questions about widely publicized reports that Abdulazeez struggled with depression, alcohol and drug dependency and that he was plagued by shame over the loss of his job in 2013 and a recent arrest and DUI charge.

Still, Reinhold did say federal officials believe the 24-year-old acted alone and they are looking into the possibility that he was self-radicalized.

"There are no indications that he had help," Reinhold told a large group of reporters Wednesday. "We're still in the early stages of figuring out what happened. Don't jump to conclusions."

One thing remains a mystery: Did Abdulazeez have a long-standing plan to attack the military that had been taking shape since he began writing about his affinity for an al-Qaida leader abroad in 2013? Or was it a spontaneous, suicidal act aimed at achieving religious redemption, brought on by psychosis and depression and a mix of substances?

The details about the weeks and days leading up to his attack and death offer competing narratives.

Unlike many other mass killers, Abdulazeez had friends, but his friendships were limited, a spokesperson for the family said. He struggled socially because of the guilt he felt about his drug and alcohol use.

"In a way, it was a self-imposed isolation," said the spokesperson, who asked not to be identified.

After his DUI arrest in April, his picture was published in the local newspaper and in "Just Busted," and family and friends have said he was deeply embarrassed. Before he lied to his parents by saying he was leaving Chattanooga on Tuesday to go on a work trip, there were multiple conversations between family members about the DUI and the upcoming court date on July 30.

Yet, even though he carried a sense of shame about not being able to act in accordance with his Muslim faith, he didn't appear to be more ideological than usual.

He fasted during Ramadan, but didn't appear to be more observant, the spokesperson said. The Washington Post reported that he did tell friends he was upset about the bloodshed in the Middle East and blamed U.S. policy, but that concern and frustration didn't seem to signify murderous intent.

On July 11, Abdulazeez bought ammunition for his guns, but he often stocked up on ammo because he liked to go to the gun range with friends, the family spokesperson said. He hunted rabbits and squirrels growing up and called himself a "Muslim redneck."

And his friends told the Washington Post that earlier this year he purchased several military-style assault weapons — AK-74 and an AR-15 a Saiga 12 pistol-grip shotgun — and drove to the Prentice Cooper State Park to practice at the gun range. But a lot of men in Chattanooga share the same hobby. Still, the guns upset Abdulazeez's father. So Abdulazeez chose to hide other guns.

Since the attack, Abdulazeez's blogs have been cited and used to argue that the Thursday attack was premeditated. He wrote on July 13 — three days before the killing — that some people thought that the Sahaba, the companions of Muhammad, were priests "living in monasteries" but that that wasn't true. "Everyone one of them fought Jihad for the sake of Allah. Everyone one of them had to make sacrifices in their lives."

In the next post, he called for action.

"Brothers and sisters don't be fooled by your desire, this life is short and bitter and the opportunity to submit to Allah might pass you by If you make the intention to follow Allah's way 100 percent and put your desires to the side, Allah will guide you to do what is right."

He told family and friends about the blog, and the spokesperson said that if he hadn't committed mass murder his writings would be considered fairly benign by other Muslims.

Before Abdulazeez left his parents' house in Hixson on July 14, his friends told the family that he was acting normally. He wanted to show off the convertible Mustang he rented and race it. He seemed in the mood to party, the spokesperson said.

But his friends said that Abdulazeez stayed out until 3 a.m. on the Tuesday night before the attack, as part of a drug-and-alcohol bender.

The next day, the family spokesperson said, Abdulazeez Googled martyrdom and whether he could be absolved of his sin if he became a martyr. The FBI has yet to release any information found on his computer or cell phone.

And on the same day, he exchanged texts with a friend about faith, the Washington Post reported.

His friend was expressing frustration, not knowing how to balance his Muslim faith with what was required of him at his job, including serving bacon to customers. Abdulazeez responded by quoting the prophet Muhammad. "Whosoever shows enmity to a Wali (friend) of Mine, then I have declared war against him."

With what they know, although there is still more to learn, the family doesn't believe that Abdulazeez was plotting his Chattanooga attack.

"We don't think this was a plan," the family spokesperson said.

In the end, the case may never be labeled as terrorism, said Jack Levin, a criminologist at Northeastern University, who had studied mass murders, including domestic terrorism, for 35 years and written multiple books on the topic. Officials are careful with the term, he said.

"We are not of one mind when it comes to defining terrorism," he said. "The FBI is usually reluctant to label a murder as an act of terrorism. If it is a terrorist episode then they have to assume responsibility. Why should they be responsible for something that is not within their purview?"

Still, the traditional idea of terrorism is evolving, said Charles Kurzman, a sociology professor at the University of North Carolina at Chapel Hill.

Post 9/11 terrorists were organized, immigrant radicals who came to the U.S. for the purpose of destruction and death, laying in wait for their moment to strike. But the attack on Fort Hood in Texas in 2009, in which a U.S. army psychiatrist killed 13 people and injured 30 others, and the attack on Chattanooga seem to illustrate a new wave.

In the case of Fort Hood, the killer, Nidal Malik Hasan, had sent emails back and forth with al-Qaida leader Anwar al-Awlaki, the same Yemen-based imam who Abdulazeez followed on Twitter and wrote about after he was fired from his job in Ohio.

Yet, whether the attack was classified as terrorism has been heavily debated. The military initially called it an incident of "workplace violence," but earlier this year the victims were awarded the Purple Heart after years of debate over whether the shooting could legally be considered terrorism.

"We are seeing a shift away from large-scale elaborate attempts to use weapons of mass destruction or other high profile plots — the hallmark of al-Qaida and its affiliates — toward a lower tech do-it-yourself strategy that is being propagated by the self declared Islamic state," said Kurzman.

Contact staff writer Joy Lukachick Smith at jsmith@timesfreepress.com or 423-757-6659.