On Monday, Suthamtewakul was stunned by the news that Alexis was said to be the shooter in the rampage at the Navy Yard.
"I can't believe he did this," he said. "He never showed any sign of violence."
But there were signs that Alexis was unhappy.
He was having a hard time trying to get on his feet, said Suthamtewakul's wife, Kristi. He helped out at the restaurant but not for pay.
"He was using this as an educational experience to help learn Thai," she said. He enjoyed making deliveries to homes, where the language was spoken. He talked about moving to Thailand.
But to Suthamtewakul, Alexis seemed "frustrated with life."
She is grieving. "He was like one of our best friends, like a brother to us and always willing to go out of his way to help us out with things," she said.
He was very frustrated with the company that contracted him to work for the Navy, according to another friend.
Alexis claimed he wasn't paid properly by the company after returning from a months-long assignment to Japan last year, said Michael Ritrovato, another former roommate.
It was unclear whether the dispute was over salary or expenses. Alexis just felt the company owed him money and had not paid him, Ritrovato said.
He is in shock over his friend's actions.
"He was an easygoing guy. I don't know of any reason for this," he said.
But Ritrovato knew Alexis was fascinated by guns. "He was ... knowledgeable with military rifles and handguns. At least he led us to believe he was. But nobody ever had the idea that he would use them in a derogatory way," he said.
Two days before the shooting, Alexis spent "a couple hours" shooting at Sharpshooters Small Arms Range in Northern Virginia before paying $419 for the Remington 870 shotgun -- after being approved by the federal background check -- and a small amount of ammunition, the store's attorney, J. Michael Slocum, said.
It is not clear whether Alexis was still living in Fort Worth area at the time of the shooting.