It would depend on the plea bargain.
If you get one that would give you immunity, the immunity is usually only good for certain crimes that they are specifically trying to investigate.
If you spill the beans about murdering some people and they are only offering immunity over your involvement of a money laundering scheme then they'll hook you up on the murder rap.
Also, if you make a deal with the state to confess to certain crimes in exchange for immunity you will also have to make sure that you get federal immunity if it applies or you'll just get charged in a different court and you'll get hooked up.
Getting immunity for murder is very rare and in the cases that I can think of the guys that did were mob guys that were going to go away for life anyway and all that they did was evade the death penalty.
Basically, you're going to jail. It was nice knowing you!