The very first CBS Radio Mystery Theater drama starred the great Agnes Moorehead,who,of course,was a veteran of the Golden Age of radio,often on "Suspense",and one of the most famous shows,"Sorry,Wrong Number"(Written by Lucille  Fletcher). "The Old Ones are Hard to Kill" was written by Henry Slesar.According to the book 'Twentieth Century Crime and Mystery Writers',edited by Lesley Henderson,the original short story was first published in 'Mike Shayne Mystery Magazine' in January,1965. 