A Massachusetts judge heard arguments Thursday as lawyers for a teenager charged with raping and killing his high school math teacher want to have his police confession dismissed as evidence.

Philip Chism’s lawyers say police coerced him into waiving his rights and making detailed statements about the murder.

Chism, 15, has been charged as an adult with murder and aggravated rape in the October 2013 slaying of Colleen Ritzer, a popular 24-year-old teacher at Danvers High School. He has pleaded not guilty.

Chism’s public defender, Denise Regan, is expected to argue in Essex County Superior Court on Friday that police never properly read Chism his Miranda rights and had continued to question Chism even after he had invoked his right to remain silent and his mother had asked for a lawyer.

Regan’s legal brief contends police pressured Chism’s mother into helping them get a confession out of her son while he was handcuffed in a police interrogation room, according to The Salem News.

Prosecutors allege in previous court filings that on Oct. 22, 2013, Chism followed Ritzer into the girl’s bathroom after school, raped her and "repeatedly asphyxiated her before or while assaulting her with a box cutter."

They said Chism put Ritzer’s mutilated body in a recycling bin and dumped it in the woods.  He also took Ritzer’s cellphone, which he destroyed, and her wallet, which he used a credit card from to buy fast food and attend a movie at the mall later that day, according to prosecutors.

Chism has pleaded not guilty to those charges as well as to attempted murder and other charges stemming from an assault on a Department of Youth Services worker while in custody for Ritzer’s murder.

Join our Newsletter for the latest news right to your inbox