One of the things I used to do at work, was pronounce people dead. It's a responsibility but it's not that hard. Dead is completely different from alive. It's hard to mistake one for the other and after several minutes, it's impossible. Little children can tell. Dogs and cats can tell. Nurses don't always notice for quite awhile. They get bogged down with the minutia and don't take in the big picture sometimes. It's an occupational hazard.
I always went through the drill. No heartbeat or breath sounds. Check a whole minute for pulse and chest expansion/contraction. Pupils fixed and dilated. Everybody deserves that, even if they are dead as a doornail.
The most important thing about pronouncing, is knowing whether or not to call the Coroner. There are several automatic flags that require notification. Any unusual or unexplained circumstances leading up to a death merits a call. If the Coroner is not notified, the body is released for burial, the medical record gets archived and you can literally get away with murder. At most hospitals, the protocol requires that the doctor be notified of a patients death and they state whether or not they are willing to specify a cause of death. If they are willing to do so, the shift supervisor can pronounce and if all other conditions are met, release the body for burial.
Sometimes a lot of interesting situations go unexamined.