You should contact a good defense attorney in your area. The statute may allow them to not save the data, but you then have an argument for Spoliation, meaning the failure to preserve evidence. It is not always available in criminal cases, but it is an argument worth making.
This response does not create an attorney client relationship and is offered for informational purposes only. Only a lawyer fully versed on the facts and circumstances of your case can properly advise you on the case. I am licensed to practice in Minnesota, not every state. You should always consult with an attorney licensed in your area on how best to proceed.