The original plea offer has no bearing on a sentence after trial other than it gives a defense attorney an argument to the judge that the DA felt this was an appropriate punishment for the acts charged. However, since you chose to exercise your right to trial (a constitutional right) there was significant expense to the state as well as a risk of loss, so typically the sentences are harsher after trial. Moreover, after trial, a judge has heard many more details about the crime and that could influence a judge's decision, especially if the judge believes a defendant was untruthful on the witness stand. Finally, when judges are inclined to give leniency they are looking to see remorse and acceptance of responsibility by the guilty party. This often can't be fully accomplished after trial as defendants need to maintain claims of innocence for appeal purposes.
Let's apply this to your case, without knowing more details, you were convicted after trial of Grand Larceny in the Third Degree. The DA had been offering six months jail (and possibly five years on probation) and your exposure is up to 7 years now at sentence. The good news is you a first offender, the bad news is the value of the property stolen is significant at the thirty to forty thousand range. In theory, the judge could sentence you to less than the original plea offer. I think it will boil down to whether or not the judge thinks that upstate time is appropriate. If I were to make an educated prediction, I would expect the judge to sentence you to two years prison.
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