Word question: Why do hospitals "pronounce" someone dead?

There was an article in today’s paper about an inmate at Atlanta’s jail who was found dead in his cell. The Sheriff’s offices took him to the nearby hospital, where the guy was “pronounced dead”.

Why wasn’t he “declared dead”?

Or couldn’t the wording have been “where the death was confirmed” or something like that?

You aren’t “pronounced born”. Why should you be “pronounced dead”?