By "the former 10-year agent" William W. Turner. "For more than forty years the F.B.I. has been beyond criticism. Now the truth is told at last --" is the claim of the back-cover copy of this 1971 paperback; blurbs wonder if FBI head "for life" J. Edgar could "ride out" the "storm" the book would create. Hoover died in 1972, so...call it.
This half-century PB isn't in great shape -- toned pages, creasing to the covers, splits and notches at the spine, rubbing/wear generally and some previous-owner scribbling, as shown -- but the pages are holding relatively steady, and the cover design is classic mid-century.