I would use /have used 'died' /'dead'. If writing a condolence message I would probably say I am sorry for the loss of your xxx if i did not know the person very well. If it was a close friend/family member I would probably say 'I am sorry to hear of xxxx death' etc.
My DD when explaining her FiL's death to her (quite young) DDs explained that he had died and that was because his turn to live was over and he was making space for a new baby somewhere!!
My garden has been ruined by ????
Trump is eyeing up Mali as his next war zone

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] that they came from "one" person.
