You die. Science often advances one dead scientist at a time. A fellow gets so much credibility that the prevailing wisdom can't change until that towering mind crooks . Mendeleev predicted elements and properties with his periodic table of the elements . This gave him enormous prestige. He was ,however , dead wrong about radioactivity. He simply refused to accept elements changing from one to another. His stubborn ways held science back until he was dead and could no longer torpedo anybody who disagreed.
I was being facetious. I think the use of the word “former” here is inappropriate.
If you had died, using the past tense would be sufficient to clarify that. “So-and-so was a scientist.”
You don’t stop being a scientist, artist or musician when you stop being paid to be one.