What your friend needs to do is to immediately get in touch with a Family Law attorney in the county where she lives, and commence an action in the Family Court (or whatever the equivalent court is in her county) via "Order To Show Cause" (which is an emergency application) seeking a grant of temporary custody.
The lawyer will draw up the appropriate petition, along with an affidavit signed by your friend which will explain the circumstances of how the child came to be in her possession. An affidavit signed by the father, sent back and forth via Federal Express, will also be needed.
It can be done, it just takes a good lawyer and some money.
If the father dies, a notarized affidavit is the best thing you can have short of a notarized videotaped statement. Plus -- and I should have mentioned this before -- the child's father should immediately make out a will and appoint your friend as guardian of the child in the event of his death (if he hasn't done so already). The father's choice of guardian may not be automatically honored but it will have a strong influence on the court.
As far as whether an Arizona court will accept the petition, that I can't say. My understanding is that wherever the child happens to be, the court there can issue an order as long as nobody is challenging it in another state (for example, if the mother was petitioning a court in Indiana for custody as well).
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