ROCKVILLE, Md. (AP) — An 18-year-old Maryland high school student was charged with planning to commit a school shooting after investigators reviewed the teen’s writings and other material, including internet searches and messages, police said Thursday.

The student was arrested Wednesday by the Montgomery County Police Department.

The investigation began after a person contacted police in the Baltimore area, saying he met the teen in a psychiatric facility. The person alerted authorities to the teen’s writings, which were labeled a fictional account by their author, according to court records. But investigators wrote that they believed the document was based on the teen’s life, not entirely fictional.

The writings, which the teen called a memoir, spanned 129 pages and included an account of a character who plans a school shooting but ultimately is taken into law enforcement custody and then receives psychiatric treatment, according to police.

But the document opened with a disclaimer calling it a work of fiction, according to court papers.

Police later obtained a search warrant and uncovered “internet searches, drawings and documents related to threats of mass violence,” officials said. Some recent searches included queries about gun ranges, prison sentences and a long list of past school shootings, according to court documents.

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Social media messages and posts by the teen also reference a desire to become famous by committing a school shooting, police wrote in charging documents.

Montgomery County Public Schools officials said in a statement that the student was completing schoolwork through a virtual learning program. They said the student “has not physically attended an MCPS school since the fall of 2022.”

Schools officials called the charges “extremely serious.” They expressed appreciation for a close collaboration with police and said the teen’s recent arrest indicates their “shared commitment to identify and address potential threats with due process before they materialize.”

Court records show the teen was hospitalized in December 2022 after threatening to “shoot up a school,” and the following month clinicians reported that the teen was talking about “suicide by cop.”