As an RN, I cannot see how legally or why in practicality LE would even put themselves in that position. It is not like a practice gives away the originals. Plus, in my experience, judges are very reluctant to allow LE to see medical records unless they can show a direct bearing on the investigation. The agency has to meet a high bar of necessity for a judge to sign that type of search warrant.
This article talks about when LE can look at patient files
http://shawnawilson.hubpages.com/hub/HIPAA-Protection-of-Patient-Privacy
Under HIPAA, personal healthcare information can be released to law enforcement without patient permission under certain circumstances. These include:
Court orders and subpoenas
Identifying suspects, witnesses, or missing persons
Reporting about victims of crime, neglect, or abuse
For any other uses, an authorization form must be signed by the patient prior to the release of information. There is special protection for:
Psychotherapy notes
Drug and alcohol abuse treatment records
Research records
Communicable disease information
HIV/AIDS status
Genetic testing
Evaluation and treatment of mental health disorders