Defense Argues Danvers Teen Was Insane, Not Responsible For Murder

Defense lawyers for the Danvers teenager on trial for the murder of his math teacher have reached a critical stage in their case. The defense admits Philip Chism strangled and cut the throat of teacher Colleen Ritzer, but his lawyers are trying to convince a jury that Chism was insane at the time and not responsible.

To make that case, their key witness is psychiatrist Richard Dudley. He took the stand today. But the defense soon ran into some obstacles.

WBUR reporter David Boeri is covering the trial and joined WBUR's All Things Considered from Superior Court in Salem.