The 18-year-old accused of taking a loaded gun to his high school in Montgomery County, Maryland, had a cache of weapons at home, including an AR-15-style rifle, and a list of grievances, prosecutors say.
Alwin Chen appeared in court Tuesday after Montgomery County police say he took a handgun to Clarksburg High School on Thursday, the day after the Florida high school shooting that left 17 people dead.
A judge ordered Chen, of Germantown, held without bond, and ordered he undergo a mental health evaluation.
Prosecutors say the following items were found in Chen's home: an AR-15-style rifle, a Glock pistol, a revolver, a detonator, a replica of an inert hand grenade and a tactical vest.
It's unclear who owns the guns, but police say there was no indication the guns belong to anyone who lives outside Chen's home.
Also, a list of grievances was found in the home, prosecutors say.
"He had written down a list of grievances and reasons he brought the gun to school with him," Montgomery County State's Attorney John McCarthy said.
Police reviewed Chen's journal and said there were no explicit threats or expression of a desire to harm anyone at the school.
County police are still working to determine Chen's motive for allegedly taking the gun to school. They said that while they did seize Chen's journal, it did not contain any specific threat.
"There is no wording regarding any threat nor any expression of wanting to cause harm to anyone at the school in his journal," police said in a statement.
One of Chen's lawyers, David Felsen, said Chen did not have access to weapons in his home, and that he did not pose a threat.
"We presented documents that Mr. Chen is a scholarship-worthy student, that even his principal said he does not present a danger," Felsen said.
He was arrested after a school resource officer received information about 2 p.m. Thursday that he might have a weapon, police said.
The officer pulled Chen out of class and asked him if he had a weapon. Chen then said he had a handgun in his book bag and knife in his front shirt pocket, police said.
The officer took the knife and loaded 9mm handgun and arrested Chen. He was charged with possession of a handgun, possession of a firearm by a person under 21 years old and possession of a firearm on school property.
Prosecutors say Chen initially said he took the gun to school for target practice after school, but that he then changed his story.
Police say Chen said he felt anxious about social interactions with his classmates.
Prosecutors say Chen had previously taken a gun to school. A Montgomery County Public Schools representative said school officials were unaware of any report that Chen had taken a gun onto school property.
Anyone with information for police is asked to call 240-773-6400.