CHATTANOOGA, Tenn. » It was a quiet spring night in East Tennessee when a police officer noticed the old gray Toyota Camry rolling slowly through downtown streets, swerving out of its lane and stopping for green lights.

Mohammod Abdulazeez – a dark-haired 24-year-old, about 6 feet tall with a sturdy wrestler’s build – was asked to step out of the car. A second officer who had arrived noticed, according to court records, that Abdulazeez’s eyelids were droopy, that he smelled of alcohol and marijuana, and that a "white powdery substance" was dusted around his nostrils. Abdulazeez told them that he had snorted crushed caffeine.

Less than three months after the April 20 drunken driving arrest that followed the traffic stop, Abdulazeez would exhort readers of his blog to put their "desires to the side" so that Allah might guide them "to what is right."

Modern-day Muslims, he wrote, speak of fasting, reading the Quran and performing other devotional acts. By contrast, he noted, the original followers of the Prophet Muhammad were people of action, with "almost every one" becoming "a political leader or an army general."

"Every one of them fought jihad for the sake of Allah," he wrote.

And Thursday, the authorities say, he fatally shot four Marines and a sailor here, then died in a gunbattle with the police. The sailor, Petty Officer 2nd Class Randall Smith, 26, died early Saturday. Now, as federal investigators talk to Abdulazeez’s friends, read his blog and interview others who knew him, a picture has emerged of a man who had come back here from a trip to Jordan last year and became angry with U.S. policy.

Detecting a Change

"All indications from the interviews is that there is something ‘different’ about him after he returned home," one law enforcement official said. "He was different but it does not appear that he was showing the typical outward signs of someone who was going to lash out violently."

Many of the people who knew Abdulazeez – classmates, neighbors, fellow athletes, fellow Muslims – spoke of the nimble way he and his Chattanooga-area family navigated the secular, suburban world here and the more conservative reality of the Middle East, where he was born and his parents, Jordanians of Palestinian descent, still have relatives.

Still, there were problems in their lives that disturbed their existence beyond neighbors’ sight. A July 30 court date for the DUI charge loomed over Abdulazeez, even as he calmly attended prayer services at the local mosque. He was dismissed from a job at an Ohio nuclear plant in 2013 just 10 days after starting, possibly after failing a drug test.

Nearly a decade ago, his father was added to, then eventually dropped from, a terrorist watch list after the authorities began an investigation, later closed without charges, into whether he had given money to an organization with possible ties to Hamas. In what might have been a wry reference to that investigation, the son wrote on his high school yearbook page: "My name causes national security alerts. What does yours do?"

Court records say his mother sought a divorce in 2009, alleging her husband physically abused her and their children and, citing Islamic law, wanted to take a second wife. The couple, now married over 30 years, reconciled.

On Saturday, the family released a statement expressing sympathy and condolences to the relatives of the service members who were killed and to those who were injured.

"There are no words to describe our shock, horror and grief," the statement said. "The person who committed this horrible crime was not the son we knew and loved. For many years, our son suffered from depression. It grieves us beyond belief to know that his pain found its expression in this heinous act of violence."

U.S. authorities said they were in the early stages of an investigation and had yet to ascribe a motive to the shootings or find evidence of ties to terrorist groups. They were looking closely at the young man’s overseas travel, which included several trips to Jordan and Kuwait, where he had relatives, most recently for seven months last year. Investigators also are trying to track the weapons used in the attacks. Officials said that Abdulazeez was armed with an AK-47 assault rifle, a handgun and two long guns, described as rifles or shotguns.

An Accomplished Family

Abdulazeez had written recently on his blog of submitting to Allah, and one friend has come forward to say he seemed changed after his most recent trip to the Middle East. But other friends, neighbors and fellow worshippers said they had not seen evidence of radicalization. Their most enduring image is of an accomplished family that, in this city of increasing diversity, seemed to be fitting in.

"If I were his dad, I would be trying to find out who radicalized my child," said Charles Jones, a neighbor. "Somebody got to that young man somewhere."

For 14 years, Abdulazeez’s parents, Youssuf and Rasmia, raised their five children in Colonial Shores, a handsome, middle-class subdivision in Hixson, Tennessee, near the banks of the Tennessee River.

Jones and his wife, Karen, who have lived next door to the family for all that time, said that when they invited the family to their home for dinner, the family responded in kind. And when the Joneses were struggling to remove an old hot tub from their deck, Mohammod and a friend "just walked over and volunteered to help."

The elder Abdulazeez is a soil engineering specialist in Chattanooga’s Public Works Department. But he often worked weekends selling cosmetics and perfumes at a flea market, neighbors said, causing him to neglect his overgrown lawn. A regular at the Islamic Society of Greater Chattanooga, which includes a popular mosque on the east side of town, he said on Facebook that he was from Nablus, a town in the West Bank; U.S. officials confirmed that he and his wife are of Palestinian descent. Citizens of Jordan, the couple also lived in Kuwait, where Mohammod was born in 1990.

Dean McDaniel, who lives two houses down from the family’s aging, two-story, light-green house, said two of Mohammod’s sisters wore headscarves in the traditional Muslim style and baby-sat for his children.

Several years ago, the Joneses recalled, Youssuf Abdulazeez invited them to the wedding of one of his daughters. They believed they were among the few Christians at the wedding, an elaborate affair in downtown Chattanooga. They said there were several hundred people there, with food and dancing and a speech by Youssuf. "They were very gracious, brought us right in and made us feel very comfortable," said Charles Jones, an Air Force veteran.

The youngest daughter, Yasmeen, now 22, played on the girls’ soccer team at Red Bank High School, said Jake Parker, who also went to school there.

Jones said the father had taught the son to shoot with pellet and BB gun practice sessions in the backyard, sometimes using bottles and cast-iron pans as targets. Youssuf came by to ask Jones whether he would mind.

"He says, ‘In my country, every young man of age has a gun,’" Jones recalled. "I said, ‘OK.’ He says, ‘My son and I, I want to teach him to shoot a gun.’"

Jones would often tell Youssuf Abdulazeez that he must be proud of the accomplishments of his son and four daughters. The oldest child, a daughter, is a chemical engineer with a Ph.D. who lives on the East Coast, the Joneses said. The second child lives in Kingsport, Tennessee. The third-oldest, Dalia, is a teacher. And Yasmeen is in graduate school at the University of Tennessee at Chattanooga, they said.

Mohammod Abdulazeez, who had been a good student in high school, landed at the University of Tennessee at Chattanooga, where he earned an electrical engineering degree and took an internship at the Tennessee Valley Authority.

His love of wrestling evolved into a love of competitive mixed martial arts – a sport his father did not view as appropriate for a Muslim. "Youssuf is a pretty strict, straight-line Muslim guy," Jones said.

A video uploaded in July 2009 to GoFightLive, a YouTube account that collects video of mixed martial arts fights, showed Abdulazeez in camouflage shorts, participating in a cage fight with a man identified as Timmy Hall. Abdulazeez dominated the fight, pinning his opponent to the mat early and pummeling him.

Chet Blalock, the former owner of a mixed martial arts gym in Chattanooga where Abdulazeez trained, said Abdulazeez would allow himself to be choked while fighting until he lost consciousness. Several times, he recalled, the young man would be out cold, revive himself, then take a brief breather before continuing to train.

"It’s a bit on the extreme side, even for mixed martial arts," Blalock said. He now thinks that Abdulazeez may have been testing his threshold for pain.

Abdulazeez worked briefly at an Ohio nuclear power plant in 2013 but was dismissed after just 10 days after the company determined "that he did not meet minimum requirements for ongoing employment."

A company spokesman did not elaborate. But The Associated Press, citing an unnamed federal official, reported that he had failed a drug test.

At the time of the shooting, he was working in Franklin, near Nashville, at Superior Essex, an Atlanta-based wire and cable manufacturer.

‘Something Happened’

In 2014, he took a seven-month trip to Jordan, saying he was visiting an uncle on his mother’s side. He had made several trips to Jordan and Kuwait before that. One friend said he had changed when he returned home. And that he had distanced himself. "Something happened over there," Abdulrazzak Brizada told CNN. "He never became close to me like he was before he went overseas.

Three days before the shootings, Abdulazeez posted two entries on a personal blog, both religious in nature. One of them retold the parable of the blind men who feel the parts of an elephant but are unable to grasp the whole. "As Muslims, we often do this," he wrote. "We have a certain understanding of Islam and keep a tunnel vision of what we think Islam is."

He also spoke of wanting to be like the original followers of the Prophet Muhammad, the ones who were people of action. "We ask Allah to make us follow their path," he concluded. "To give us a complete understanding of the message of Islam, and the strength to live by this knowledge, and to know what role we need to play to establish Islam in the world."

Whatever was going on inwardly, some like Ali Shafi, who attends prayers at the Islamic Society, said he did not observe much change in Abdulazeez upon his return from Jordan. Shafi, 16, said he was a longtime family friend of the Abdulazeezes. Mohammod sometimes led religion classes at the Islamic Society. At times, the two young men played basketball in the gym next to the prayer rooms.

When he began coming to the mosque after his time away, Abdulazeez was the same as ever, Shafi said: That is to say, he was serious about religion yet easygoing.

During the monthlong celebration of Ramadan, which just ended, Abdulazeez was a regular at the Islamic Center, Shafi said. On Wednesday, he stayed with other faithful to read the Quran late into the night.

It was sometime around midnight Wednesday when Shafi saw his friend for the last time. He was leaving the mosque in the old gray Camry.

Shafi asked how he was doing. Fine, Abdulazeez responded. "Alhamdulillah," he added – Arabic for "thanks be to God."

Then Abdulazeez drove off into the darkness.

© 2015 The New York Times Company