Colleen Ritzer

Phillip Chism listens to testimony during his trial at Essex Superior Court in Salem, Mass., Monday, Dec. 7, 2015. A psychiatrist testifying at the trial of the Massachusetts teenager charged with killing his math teacher said the teen suffered from psychosis. Chism is charged with rape and murder in the October 2013 slaying of 24-year-old Danvers High School teacher Colleen Ritzer. (Aram Boghosian/The Boston Globe via AP, Pool) MANDATORY CREDIT

What’s Next for Philip Chism?

Chism, now 17, will serve at least 40 years for the rape and murder of Danvers teacher Colleen Ritzer, and experts will parse that sentence. But what do we really know about how he’ll serve that time?