On the Tuesday before the shootings, he seemed "engaging, present, connected," Bell told CNN. On Wednesday, he seemed markedly different -- stressed and hurried, she said.
"He said he was extremely tired, exhausted," Bell said.
Alexis' autopsy is expected to be completed by the end of the day Wednesday, according to a spokeswoman for the Office of the Chief Medical Examiner in Washington.
The Navy moved to discharge Alexis in 2010 due to what two Navy officials described as a "pattern of misconduct." Those incidents involved insubordination, disorderly conduct, unauthorized absences from work and at least one instance of drunkenness, a U.S. defense official told CNN.
Because of a lack of evidence, authorities were unable to get a general discharge that might have had an impact on his ability to get civilian work, the official said. Instead, he was given an honorable discharge and later hired as a civilian military contractor after passing security reviews.
There also were run-ins with police, beyond the Newport incident. Seattle police arrested Alexis in 2004 on accusations that he shot out the tires of another man's vehicle in what he later told detectives was an anger-fueled "blackout." He was arrested in 2008 in DeKalb County, Georgia, on a disorderly conduct charge.
Friends said Alexis didn't seem capable of such violence.
"Aaron was a very polite, very friendly man," said Kristi Suthamtewakul, a friend and former housemate.
But he was frustrated about pay and benefits issues after a one-month contracting stint in Japan last year, Suthamtewakul said.
"He got back and he felt very slighted about his benefits at the time," she said. "Financial issues. He wasn't getting paid on time, he wasn't getting paid what he was supposed to be getting paid."
"That's when I first started hearing statements about how he wanted to move out of America," Suthamtewakul said. "He was very frustrated with the government and how, as a veteran, he didn't feel like he was getting treated right or fairly."
Friend Melinda Downs described Alexis as "very intellectual" and of "sound" mind -- saying if he did hear voices, "he hid it very well." The two spoke as recently as a week ago, at which time Downs said she had no hints of what was to come.
"It is like Dr. Jekyll and Mr. Hyde," she said. "Who was this guy?"
The revelations about Alexis' past have led to questions about whether he should have retained his security clearance after leaving the Navy or been allowed to obtain a job working on military bases.
The Experts -- the contracting firm for which Alexis worked for about six months over the past year -- said the last of two background checks it conducted in June on Alexis "revealed no issues other than one minor traffic violation."
Rep. Michael McCaul, chairman of the House Homeland Security Committee, said Tuesday that he felt Alexis' infractions "were kind of swept under the rug."
"It is real easy to just pass the buck along to another military base or, in this instance, a defense contractor," the Texas Republican said. "...There are so many red flags that popped up in this case."
On Wednesday, Defense Secretary Chuck Hagel announced the agency would examine security at bases worldwide. He also said his deputy, Ashton Carter, will look at procedures for granting and renewing security clearances.
"There are many questions that are going to be asked, need to be asked, many reviews, and the intensity of those reviews have to go down to every aspect, the security of the physical premises, security clearance, standards of that security clearance, are they strong enough? Why do we do certain things the way we do?" Hagel said. "We need answers, and we will find those."