WASHINGTON — In the early 1950s, the virtuosic jazz pianist Hal Schaefer was working behind the scenes at the 20th Century Fox studio in Hollywood as a musician, musical arranger, and vocal coach. He tutored many film stars in the finer points of singing, but none more glamorous than Marilyn Monroe.

The two became lovers, which is how the little-known vocal coach became embroiled in a Hollywood scandal involving three of the biggest celebrities of the time: Monroe, Joe DiMaggio, and Frank Sinatra.