The USS Juneau, mentioned by Detective Brody, was a light cruiser sunk at the Battle of Guadalcanal in November 1942. Its loss was notable for the deaths of five brothers from the one family, the Sullivans.
The play ran on Broadway for 581 performances, from 23 March 1949 through 12 August 1950. It starred Ralph Bellamy as Det. McLeod. Meg Mundy played his wife. Maureen Stapleton played Miss Hatch, and James Westerfield was Lou Brody.
William Wyler engaged Dashiell Hammett to adapt the Sidney Kingsley play for the screen. After three weeks Hammett returned the advance check to Wyler, saying he couldn't do it. At the time Hammett was under scrutiny for his alleged Communist affiliations and was blacklisted.
The trivia items below may give away important plot points.
As it was impossible to film the movie without portraying the killing of Detective McLeod, this movie resulted in another amendment to the Production Code. From December 20, 1938 to March 27, 1951, there was a rule forbidding the display of law enforcement officers (including detectives, security guards, etc.) dying at the hands of criminals. From March 27, 1951 onward, the Production Code allowed such portrayals if they were "absolutely necessary to the development of the plot". (This information comes from the book "The Dame in the Kimono" by Leonard Jeff & Jerold Simmons, New York: Grove Weidenfeld, 1990).