CNN  — 

The teenager accused of carrying out the mass shooting at Santa Fe High School on Friday was known as a quiet student who often wore a trench coat to school.

Dimitrios Pagourtzis, 17, is being held on charges of capital murder and aggravated assault of a public servant in relation to the school shooting, Texas authorities said.

Pagourtzis allegedly used a shotgun and a .38-caliber revolver to kill 10 people – eight students and two teachers – and injure 13 others, and he confessed that he acted alone in the shooting, according to a probable cause affidavit.

Here’s what we know so far about the 17-year-old suspect:

Dimitrios Pagourtzis is pictured in a Galveston County Sheriff's Office booking photo.

A quiet student

Dimitrios Pagourtzis (pronounced: di-MI-tree-oas pag-OR-cheez) began attending Santa Fe High School in August 2015, according to his Facebook page.

Pagourtzis played on the 2016 JV football team and appeared on the 2015-2016 boys freshman football team. He was listed on the Santa Fe Junior High sixth-grade honor roll in 2012.

“I’ve talked to him once or twice. I had my advisory class, which is after third period, with him,” Santa Fe High student Mateo Twilley said. “He was really quiet, and he wore, like, a trench coat almost every day.”

This image of a trench coat was taken from a Facebook page belonging to  Dimitrios Pagourtzis.

Student Aidan Gomez noted that Pagourtzis always wore a trench coat.

“He was kind of a quiet kid,” Gomez said. “Every time you’d try to start a conversation with him he’d just kind of like laugh, wouldn’t really continue on with the conversation. … He didn’t like interacting with other students.”

Gomez said he was surprised when he heard Pagourtzis was suspected of being the shooter.

“I didn’t think he was that kind of kid,” Gomez said.

‘Never seen a problem’

Nicholas Poehl, one of Pagourtzis’ attorneys, said that his client did not appear to have a history of mental health or legal issues.

“At this point, from everything we know, it doesn’t appear like this kid had the kind of warning signs of someone that you would normally associate with someone involved in something like this,” he said.

Pagourtzis lived with his parents and had not previously been employed, according to court documents.

Neighbors in nearby Alvin, Texas, say Pagourtzis grew up there on a tree-lined street.

“Never seen a problem out of that child,” said Richard Wallace, recalling how Pagourtzis would come around every year for Halloween.

Another neighbor, Bobbie Owen, said Pagourtzis and his younger sister helped her carry in Christmas packages last year.

Bertha Bland, 54, said her grandson Stephen Bland had been friends with Pagourtzis since the fourth grade. The two would eat lunch together and play video games after school, up until sometime last year when Pagourtzis pushed Stephen away for new friends for unknown reasons, she said.

Bland said her grandson and Pagourtzis both had an interest in guns and violent video games. Pagourtzis’ mother told Bland