The Massachusetts parents accused of killing their 4-year-old daughter by overdosing her with prescription drugs will be tried separately.

Assistant District Attorney Frank Middleton said in court Wednesday that prosecutors decided to hold separate trials for Carolyn and Michael Riley after the judge ruled certain statements each of the Rileys made might incriminate the other and could not be heard. Those statements could be used in separate trials.

The judge on Monday denied a defense motion to dismiss murder charges against the Rileys. Their lawyers argued that the murder indictment should be thrown out because a new medical report from a prosecution expert acknowledges that the girl had pneumonia. The defense claims that caused her death.