Today I Hang (1942)

Henry Courtney, a wealthy importer is found murdered and the famous DeNormand necklace has been stolen. The false testimony of two witnesses, Rand and Hobbs, puts Jim O'Brien in the shadow of the hangman's noose. Martha Courtney, widow of the murdered man and Jim's former sweetheart is convinced he isn't guilty, and promises crooked lawyer Roger Lanning the necklace - which Jim doesn't have - if he can arrange for Jim's escape. Rand and Lanning killed Courtney, but Lanning doesn't know that Rand has the necklace.