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Massachusetts teen charged in teacher’s killing to face second rape charge

Dec. 4, 2013: Phillip Chism, 14, from Danvers, Mass., is lead into the court room at his arraignment in Salem Superior Court in Salem, Mass. Chism, accused of raping and killing Danvers High School teacher Colleen Ritzer in October.

Dec. 4, 2013: Phillip Chism, 14, from Danvers, Mass., is lead into the court room at his arraignment in Salem Superior Court in Salem, Mass. Chism, accused of raping and killing Danvers High School teacher Colleen Ritzer in October.  (AP Photo/The Eagle-Tribune, Paul Bilodeau, Pool, File)

A 15-year-old Massachusetts boy charged with killing his math teacher is returning to court Thursday for arraignment on a second rape charge.

Philip Chism is charged in the October killing of Colleen Ritzer, a 24-year-old teacher at Danvers High School.

Chism has pleaded not guilty to charges of rape, robbery and murder. He was indicted last week on the initial rape charge. In court documents filed last week, state police say Chism admitted killing Ritzer but denied raping her.

Police say they want to conduct a forensic examination of Chism's cell phone to see if he memorialized the killing in photos, video or audio recordings.

Authorities allege Chism raped and killed Ritzer after she asked him to stay after school for extra help.

Chism's arraignment is in Salem Superior Court.