The “boarding school bandit” is facing big-time detention — a mandatory minimum of 15 years in prison, prosecutors said yesterday of his alleged rubber-revolver rob spree in Central Park.

Jesse Wasserman, 17, a psychotherapist’s son from New Rochelle, was released after a day in custody on $150,000 bail.

When Wasserman was busted before dawn Thursday, it was moments after his third alleged robbery, said assistant district attorney Mao Lin.

Defense lawyer Norman Steiner said of the suspect’s parents: “They stand by him and look forward to a time in the near future when he moves on to better things.”

The three robberies happened Wednesday and Thursday along East Drive.