You can put の after a verb or adjective to do this. Example:青いのください。 The blue one please. Example: あの亡くなったの… The one that disappeared... of course being specific works too Example: あの亡くなったやろ that scum bag that disappeared

亡くなる means for someone to die(more round about and subtle way to express death than the word 「死ぬ]） 消える（きえる）is the word your looking for. As for grammatically we would not really use の to express that meaning while it is acceptable in Justin's first example sentence as a casual speech it cannot be used in the same way with verbs or in proper Japanese.　There needs to be a little bit more context behind what the "one" that disappeared is in order for me to fully answer your question.