The ability to expunge charges has nothing to do with whether there was a plea agreement involved. In Dressner v. Commonwealth, the defendant had a marijuana charge amended to reckless driving as part of a plea agreement and plead guilty to the reckless driving. The Supreme Court of Virginia held that she was able to have the marijuana charge expunged. Your case is even more clear cut - your felonies were dismissed, which means that you are eligible for expungement (unless they were dismissed through a diversion program, but that doesn't seem to be the case here). Since they are felonies, you will have to show that you are likely to experience "manifest injustice" which essentially means that you are losing opportunities because these dismissed charges appear on your record. If you can demonstrate that you are not able to find work because of the dismissed charges, then the court will have to grant your request to expunge the charges, even if the prosecutor objects.
You would need to speak with an attorney in your area about the process. A lot will depend on the circumstances of the plea. Were the other charges dropped in exchange for your guilty plea? If so, the Commonwealth will likely object to the expunction.
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