I bought a car from the dealer in 2012 with odometer 36xxx with the loan. In 2017 I cleared my loan and tried to sell my car. Meantime I checked the carfax which shows 100xxx potential odometer rollback done by the dealer.
For most criminal felony fraud charges the statute of limitations is 3 years. Under some circumstances the SoL can be extended. For civil claims, the exact end date of the fraud could be argued as a continuing matter. Be aware a Carfax "potential" rollback flag does not prove that fraud did in fact occur. If you are seeking criminal charges you will need to contact your local police/DA. If you are seeking civil claims you will need to contact a directly lawyer. You can also pursue both civil and criminal charges concurrently.