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A man who allegedly threatened to commit a mass shooting at UCLA wrote an 800-page manifesto that contained antisemitic content.

The LA Times identified the suspect behind the threat to carry out the mass shooting as Matthew Harris, 31, a former UCLA lecturer and postdoctoral fellow.

Harris was arrested by Colorado law enforcement this week.

According to StopAntisemitism.com, Harris, who made the threats to the university’s philosophy department, wrote an 800-page manifesto that contained antisemitic as well as racist and misogynist beliefs.

"The material includes a video entitled ‘UCLA Philosophy Mass Shooting’ and an 800-page manifesto with specific threats towards some members of our department," said an email that UCLA send to students, the LA Times reported.

The threat led to the cancelation of in-person classes at UCLA on Tuesday. Instead, classes took place online. Police also evacuated businesses, schools and houses in the area where Harris was located, city officials said. A crisis intervention team was used to help with Harris’s surrender to police.

The Boulder Police Department started an investigation after UCLA provided them with threatening emails and the 800-page manifesto written by Harris. UCLA police had contacted Boulder police after locating Harris there, ABC7 reported.

"Upon reviewing parts of the manifesto, we identified thousands of references to violence, stating things such as killing, death, murder, shootings, bombs, schoolyard massacre in Boulder, and phrases like burn and attack boulder outside of the university," Boulder Police Chief Maris Herold told reporters.

Michael J. Beck, UCLA’s administrative vice chancellor, said in a statement that he was “greatly relieved to share that law enforcement officers in Colorado have taken into custody the individual who made threats against some members of our UCLA community.”

According to media reports, Harris had been on leave from UCLA after a female professor from the University of California, Irvine philosophy department was granted a restraining order against him for sending threatening emails that stated he wanted to “hunt” her and “put bullets in her skull.” The emails were sent to Harris’ mother who contacted the woman.

Court documents also said that a separate incident in which the suspect had been found guilty by UCLA of sending violent and obscene content to students resulted in him being put on leave for “predatory behavior.”