Yes, you must consult an attorney. When you read N-400 application Part 10 questions 17 and 18. Note that these questions do not ask you if you comitted a crime in the US specifically, so this will be for the rest of the world as well. Besides with the new background check they have in place, they will find out anyways as they check with other countries where you have resided in the past. This is one reason of the background delays, as they do check in your country of birth and residence. They will find major crimes reported by that country(ies). I have friends in the US government and I know FOR A FACT that they do this. USCIS may not care about the offense "whatever that might be", but I can asure you that they do care for an applicant NOT disclousing that information in your application.
For the rest of the guys here, I know you are trying to help, but please DO NOT give an advice unless you know what you are talking about. Guessing doesnt help but rather hurts. A trafic ticket is NOT the same as kiling someone even if it was an accident.
So again, consult with an attorney or better two and see if they have the same advice before you file as the USCIS will know about this either from you or from the background check. I am sure a good attorney will ask you for the court pappers before he/she can give you an advice, so be prepared to have the documents.
Good luck, Shaffi