Bryan Kohberger appeared expressionless as a judge asked if he murdered four Idaho college students in their off-campus home, answering “yes” to each name called out in the courtroom Wednesday.

With a series of “yes” replies to a judge, a man accused of killing four Idaho college students pleaded guilty in exchange for life in prison and no death penalty. But left untold so far: What motivated Bryan Kohberger to commit the middle-of-the-night knife attacks and why those victims?