You made an interesting point that caused me to wonder if she may have belonged to a denomination whose practices might be less well known. I'm not sure if any of the more mainstream Christian denominations would be against resuscitation. I am Baptist and we don't have a problem with it, at least I've never heard anyone speak out against it and I've been in the church my whole life. For instance, I've known many church members who arrived at hospitals in cardiac arrest or diabetic coma, their heart stops, and they are revived and are very thankful for it. We believe in doing what you can to save a life as long as it does not prolong suffering, such as a a case where resuscitation would only postpone death and lead to a long and painful death. My mom, although Christian, had a DNR order because she was terminally ill with cancer. Doing CPR would be of no benefit to her if her heart stopped because it would only prolong her pain and suffering. I have heard about Jehovah's Witnesses and blood transfusions, also organ donation I believe, and I have heard that Seventh Day Adventists hold the same beliefs. I have also heard that Christian Scientists don't believe in medical intervention. Someone who knows more about the study of religion could better answer our questions. I wouldn't want to say something wrong and offend anyone because that definitely isn't my intent. If our UID had a faith, just judging by appearance alone, I would guess either Christian or Jewish. I would seriously doubt Hindu or Muslim for instance.
On another note, my mom specifically listed on her living will that she was not to be autopsied. It was her personal belief that an autopsy violated the body and was a mutilation and she had a great fear of somebody cutting her up after death. It had nothing to do with any religious belief, it was just something she personally hated the thought of. She kept making me promise I would not allow it, although there is no need for an autopsy when you are known to have died a natural death like hers. I wouldn't be keen on the idea either, just out of respect for the body. Maybe our UID just didn't want herself mutilated after death. Unless a death is suspicious, or is unattended without an obvious cause, autopsy is not required so far as I know. Probably LE thought at the time that it was an unnecessary procedure and expense.