You can contact the DA, but the chances are very, very, very slim that the criminal justice system would get involved when there is no evidence of criminal activity.
Now, if you husband were to appointed as the estate's personal representative and gains access to all his mother's records and finds suspicious activity (like, say, forgery), then the DA might be interested.
The will only controls the disposition of assets that are part of the probate estate. Not assets co-owned with right of survivorship, or assets with designated beneficiaries (Pay on Death designations, Transfer on Death designations, life insurance with a beneficiary, IRA's with beneficiaries, etc.)