Not sure what "adjudicated as mentally defective" means exactly but would be more than happy to speak to you about doing some research into whether you can get some relief.
Take up Mr. Gerash on his offer. I don't think this has anything to do with money and you paying the attorney. I think that you are just raising an issue that most of us, if not all of us, have not seen before. I have not seen it in 24 years as a judge, prosecutor, and private attorney. Expungement in CO applies to juvenile records and sealing applies to adult criminal records. So, this is a weird and unusual case. Any attorney that you hire will need to do significant research to see if the case can be expunged.
The information provided in this answer does not create an attorney-client relationship. If you are interested in his legal services, feel free to call Chris at (303) 409-7635 at his law office in the Denver Tech Center. All initial consultations are free of charge.
Give either one of my colleagues a call -- they are excellent attorneys with experience in the criminal justice system.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.