In general, the police have broad powers to make inquiries that they believe would help them in their policing work.
As a medical professional, important to understand your professional duty of confidentiality towards your patients as well as your general duty to report a serious crime.
In general, "causal enquiries" from the police should not be entertained, eg "did you have a man come in with a knife wound yesterday?". Phone enquiries should also be answered with the advice to make the enquiry through official channels.
There is almost no circumstance where you should provide information to police without the patient's consent.
All hospitals have a legal department or a risk management unit as a point of liaison with legal agencies, they should be contacted at all instances for advice. Help can also be obtained from your medical indemnity organisation.
The Health Records and Information Privacy (HRIP) Act 2002 (NSW) requires staff to protect the privacy of health information. A comprehensive guide to how these affect your work is available in The Privacy Manual for Health Information, which can be accessed here.
Section 11.2.7 of The Privacy Manual deals specifically with information given to the police. It can be accessed here.
Read the advice from AMA and medical indemnity organisations:
AMA:
Avant:
MIP:
The Office of the Australian Information Commissioner has published the Guide to Health Privacy, which is a comprehensive guide with numerous examples. Click here for Chapter 3 - Using or disclosing health information.