 -- FBI agents have found evidence that Chattanooga shooter Mohammod Abdulazeez was following a radical American member of al Qaeda online in 2013, as well as pages of writing that showed the young man was suicidal and looking for a way to absolve what he considered were his sins, according to a representative of Abdulazeez's family.

Video tapes of Anwar al-Awlaki, the high-profile American al Qaeda cleric and recruiter, have circulated on the internet and have been popular in jihadist circles long after al-Awlaki's death by American drone strike in September 2011.

Monday U.S. officials told ABC News that in 2013 Abdulazeez did online research for militant Islamist "guidance" on committing violence. The Internet searches were discovered on electronic devices such as his smartphone analyzed over the weekend by the FBI Lab in Quantico, Virginia, several counter-terrorism officials confirmed to ABC News.

At the time, diary notes kept by Abdulazeez revealed he wrote about having suicidal thoughts and "becoming a martyr" after losing his job due to his drug use, both prescription and non-prescription drugs, the family representative said earlier today. His family has said Abdulazeez suffered from depression and other mental issues.

But there is no evidence so far that Mohammod Abdulazeez, 24 -- whose family insists he was deeply troubled and mentally ill -- was inspired by or directed by ISIS to carry out a bloody attack on U.S. military targets of the sort the Syria and Iraq-based terror group has publicly called for over the past year, the officials said. Al-Awlaki was a high-profile member of al Qaeda, from which ISIS -- once an al Qaeda affiliate in Iraq -- publicly split in recent years.

Abdulazeez killed four Marines and mortally wounded a Navy sailor during his rampage last week. Local authorities said that Abdulazeez was likely killed on site by police responders.

"I don't think that there is any evidence it was ISIL [ISIS]-inspired. He may have been seeking some religious guidance to conduct an act. He could readily find that anywhere online," a senior official briefed on the investigation told ABC News.

Some of Abdulazeez's friends, who often partied with the young engineering graduate and went shooting together at local ranges, may have known he was seeking answers in his religion but they do not appear to have been aware he was about to take lethal action that he may have become convinced would earn his place in Heaven, the officials said.

"We may never know what his ultimate motivation was," the senior official added.

The Reuters news agency reported Monday that some officials said Abdulazeez had been inspired by "general propaganda" by jihadists and not specifically by ISIS, al Qaeda or other militant groups. One friend, James Petty, told ABC News that Abdulazeez actually loathed ISIS for its brutality. “He believed that ISIS was not a group to go towards” and did not think that “ISIS was even Islamic,” said Petty.

Many jihadis who oppose killing innocent civilian "disbelievers" still view the military as a legitimate target because U.S. troops are the nation's blunt instrument of foreign policy.

FBI Visits Friend's Home

Overnight in Chattanooga the FBI continued its investigation by questioning friends of the shooter and visiting the apartment of one friend, whom a source close to the investigation told ABC News is believed to have gone "joy riding" with Abdulazeez in a rented convertible two days before the deadly incident.

FBI Chief Ed Reinhold spoke to reporters late Monday, saying the friend was not considered an accomplice and the FBI just wanted to question him.

More than two dozen additional FBI agents traveled to Chattanooga to assist in running down leads and, in part, to help piece together exactly what Abdulazeez did in the days and hours leading up to his rampage.

The family representative told ABC News Abdulazeez rented a silver Mustang Tuesday, showed up at the local mosque and took the friend on a “joy ride” until 3 a.m. Abdulazeez did not sleep at his parents’ home for the next two nights.

“He bragged about [the car], and was showing it off to friends about how fast it would go,” the family representative said Sunday.

Then, on Thursday, Abdulazeez shot and killed the four Marines and fatally wounded the Navy sailor after opening fire on two unguarded military facilities in Chattanooga.

The family representative said Abdulazeez had a number of guns in his house and often used them to go hunting or for target practice with friends at nearby firing ranges. FBI agents recently focused on the Walmart in Hixson, where officials tell ABC News Abdulazeez bought ammunition for his guns on July 11. Two young men, seen with Abdulazeez in the store, are also being sought for questioning although they are not believed to be accomplices.

The family representative said Abdulazeez's family sought, without success, to get him treatment for his mental illness, and to keep him away from a group of friends with whom he would drink and smoke marijuana.

Abdulazeez's family released a statement Saturday saying that there are "no words to describe our shock, horror, and grief."

"The person who committed this horrible crime was not the son we knew and loved," the statement said. "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."

Still, for the FBI, the psychological profile of the disturbed young man does not explain why he chose two U.S. military targets, seven miles apart, for his deadly mission.

Editor's Note: A previous version of this report said the shooting occurred last Wednesday. It took place Thursday. This report has been updated.

ABC News' Barbara Schmitt, Brian Epstein, Alexander Hosenball, Rhonda Schwartz and Lee Ferran contributed to this report.