Can you change your plea at a sentencing hearing?

Question Details: After being lead to believe that the police had seen my 17 year old driving at the time they gave him a ticket for DUI, I encouraged my son to plead guilty at his arrainment hearing. After pleading guilty it came to light that the arresting officers had not actually caught him in the act of driving. Is it possible to hire an attorney and change his plea at the sentencing hearing? Important Notice