Acid bath murderer....
...I'm wondering whether the real-life case of John Haigh (http://en.wikipedia.org/wiki/John_George_Haigh) inspired the method of body disposal used in the film. Haigh was arrested shortly after the 20th of February 1949 and the case would instantly have become a national sensation.
According to IMDb, Obsession was released in the UK on August 3, 1949, exactly a week before Haigh was executed by hanging; presumably filming took place during spring of that year. The screenplay was by Alec Coppel, adapted from his own book, A Man About A Dog, which was released in 1947. So the obvious question is: did the book feature the acid bath or did Coppel/Dmytryk rework the script to that end?