Exactly.
Now where does it say what you claimed it does? Where does it say that Tippit was pronounced DOA at 1:15?

Hi Bill, it's simple logic, if someone is "dead on arrival" that can only mean that they died earlier and somewhere else and it's the job of the doctor at the hospital to make an educated decision to the time of death.
For instance if someone dies sometime during the night and is taken to the hospital the time of death isn't the time the ambulance arrives but the doctor will evaluate the body for temperature, rigor mortis and other stuff and give their professional opinion of the time of death.

JohnM