Uh, how would they be sentenced to death, since their crimes (even in the worst-case scenario), don't approach the death penalty level anywhere in the U.S.?
First of all, Massachusetts (where Phoebe Prince died) doesn't have the death penalty (Connecticut did, but abolished it a couple of years ago). Second of all, the prosecutor IOTL got a lot of criticism for (supposedly) overcharging the perpetrators, so the criticism here would be even worse, particularly since she used a penalty that isn't in effect in Massachusetts...