death

Does anyone know how a date of death is officially arrived at for those deceased whose time of death can't be estimated with any certainty? For example, on their death certificate or their grave stone. My deceased are going to be one drowned and washed up some time later and one dead of injury...

Searching the audible 2 for 1 sale had me appalled at the lack of original ideas out there. Probably 2/3rds of the books were series and those series were basically fan fiction for other series. Which led me to trailers of movies coming up. Same thing. The English-speaking world seems stuck...