Charged as an adult in the shooting at a Baltimore County high school, 15-year-old Robert Wayne Gladden Jr. was held without bond Tuesday as a portrait of a withdrawn and occasionally bullied student with a troubled home life emerged through interviews with classmates and court documents.

The suspect, who underwent a mental health evaluation, was charged with attempted murder and assault in the cafeteria shooting at Perry Hall High School on Monday, the first day of classes. Gladden’s attorney, George Psoras Jr., cautioned against a rush to judgment, saying the bullying his client endured pushed him to a breaking point.

Gladden’s stepfather, with whom he lived along with his mother and older sister, was also arrested Monday after police searched their Kingsville home and found marijuana and firearms in the home. The stepfather, Andrew Eric Piper, 43, was previously convicted of grand theft, prohibiting him from possessing firearms, police said.

The shotgun allegedly used in Monday’s shooting, though, came from Gladden’s father’s home, where the teenager sometimes stayed, police said.

Gladden is “devastated” and “out of it,” unable to comprehend the charges against him, Psoras said. Police interviewed him for hours without a lawyer on Monday and took a lengthy statement, Psoras said.

According to charging documents, Gladden entered the school cafeteria with a shotgun and began shooting. He fired the first shot at a lunch table and struck Daniel Borowy, 17, in the back, police said.

Borowy remained in critical condition Tuesday night at Maryland Shock Trauma Center, where he had been airlifted. Police said it didn’t appear that Gladden targeted Borowy.

A deeper picture of the suspect emerged Tuesday as students returned to school under heavier security and after many attended a morning prayer vigil for Borowy.

Friends and classmates described Gladden as increasingly alienated and downcast, “one of the weird kids” who got picked on at school, his friend Collin Asbury, 17, said Tuesday.

“He was just so mentally and psychologically injured,” Asbury said of Gladden, adding that doesn’t excuse violence. “When people act so harshly to someone for such a long period of time, it has an impact.”

Another student, Trent McCallum, a junior, said he noticed a change in Gladden last school year. He started wearing baggy black clothes and dying his hair black, and some students started to mock him, McCallum said.

“Something big changed in his life,” McCallum said. “He was acting sad, and he was lonely, but I think he had good in him.”

At 6:27 a.m. Monday, on a Facebook page in which Gladden lists his employer as “The Manson Family” and calls the Columbine shooters “inspirational people,” he posted: “First day of school, last day of my life.”

Baltimore County Police Chief James W. Johnson said Gladden took the school bus, carrying with him a double-barrel shotgun, 21 rounds of 16-gauge, 7.5 shot and a bottle of vodka. He went to two classes, then the cafeteria for lunch, Johnson said, first placing a black backpack with the shotgun, disassembled, in a nearby bathroom.

Students said some kids were throwing food at Gladden in the cafeteria — and not for the first time, said Matt Pedata, 19, a senior who had an art class with him last year. “He was picked on all the time,” Pedata said.

Police said that although the students who threw things at Gladden on Monday had already left the cafeteria, he went to the bathroom to retrieve and assemble the gun.