Evidence collection on unconscious patient

Thanks for your quick response. Getting consent is not the issue. It seems like the issue is boiling down now to whether or not we should even do the kit. The most recent case was a female with a gunshot to the head, on life support. Essentially they were waiting for her respirations to cease, and expected this with in 24 hrs. We were aware that the evidence may have already been compromised.
I am also aware that our Coroner has collected post mortum kits with sucess as the body temp decreases etc, and evidence can still be obtained.
So the issue became : Do we do the kit now or wait and let the Coroner complete it? I did do the kit but now I am having second thoughts. Would it have been better to wait and let the Coroner do it?
I base this primarily on how difficult it is to position the person in order to view the cervix ( if possible) and gather evidence. In a way I feel more damage can be done. I have also done another case where the patient woke up after 2 weeks and was able to identify the perpetrator.
As a team we are now trying to set up protocol regarding completion of a kit on an unconsious patient when they are on life support. I would appreciate anyone's feed back regarding their policy on this.