Jury finds Massachusetts teen guilty in teacher's 2013 murder

Chism Found Guilty of Murder

A Massachusetts jury on Tuesday found a teenager guilty of raping and murdering a math teacher at his suburban high school in 2013, after about nine hours of deliberations.

In finding 16-year-old Philip Chism guilty, the jury rejected the defense's argument that he was suffering from a psychotic episode at the time of the 2013 attack and therefore not criminally responsible for his actions.

SEE MORE: Jury sees video of Chism following teacher in school

Chism was 14 when he committed the killing at his high school in Danvers, Massachusetts, north of Boston. But he was tried as an adult and could be sentenced to life in prison.

He was tried as an adult and could be sentenced to life in prison.

As the verdicts were read, Chism displayed the same appearance he maintained in court throughout the trial, staring straight ahead without emotion. Members of Ritzer's family wept.

Prosecutors presented voluminous evidence during the month-long trial, including school surveillance videos, to support allegations that Chism followed Ritzer into a bathroom after school, raped and strangled her, and carted her body in a recycling bin to a wooded area off campus.

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In her closing argument on Monday, Essex County prosecutor Kate McDougall stressed that Chism's actions were methodical throughout the day of the attack and included bringing bags to school containing a box cutter, gloves and a change of clothes, and later shopping at a store for a hunting knife.

"Are his actions ... consistent with psychosis or are they consistent with Philip Chism doing what he wants?" McDougall asked the jury.

Chism's attorneys had argued that he suffered from a severe mental illness that had gone undiagnosed for years. Citing the testimony of a psychiatrist who examined Chism, defense attorney Denise Regan said the strain of moving from a supportive community in Tennessee to starting as a freshman at a new high school had triggered a psychotic break.

"Philip Chism was under enormous stress," Regan said in her closing statement. "What other than overpowering mental illness could cause him to commit these acts?"

The trial at Essex County Superior Court in Salem, Massachusetts, was occasionally delayed by Chism, who at one point refused to return to the courtroom after a break telling his attorney that he was "about to explode."

Watch more coverage:

Chism Seen on Video Following Slain Teacher Into Bathroom

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