An Essex County grand jury has brought a new count of aggravated rape against Philip D. Chism, the Danvers 15-year-old accused of murdering popular high school math teacher Colleen Ritzer in October, the district attorney’s office said today.

The grand jury was recalled this morning and presented with new evidence before it handed up its indictment, Essex District Attorney Jonathan Blodgett’s office said.

The youthful offender indictment alleges that Chism forced Ritzer, who was Chism’s math teacher at Danvers High School, to have sexual intercourse. Aggravated rape charges are brought when there is serious bodily harm or when the rape was committed during another felonious and violent crime, prosecutors said in a statement.

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Chism already faced an aggravated rape charge in the Oct. 22, 2013, attack on Ritzer, 24, of Andover because he allegedly sexually assaulted her with an object. Chism was 14 at the time of the alleged attack.

Chism was indicted by the grand jury for the first time on Nov. 21 on charges of first-degree murder and armed robbery, as well as the initial rape charge.

Chism allegedly attacked Ritzer when she stayed after school to talk with him about an upcoming exam. When the indictment was first announced, Blodgett said Chism had allegedly committed “horrific and unspeakable acts.”

Chism’s next court hearing was slated for Thursday in Salem Superior Court. Prosecutors said it was likely he would be arraigned on the new charge at that time.