Dan, I'm not remembering the murder that you suggest Russell committed herself--if you are referring to Eric Lasser (Lowell Gilmore), her partner in the jewel robbery scheme, he is killed by Ladd in the final shootout.
That detail does not detract from the rest of the analysis, however.
My sense is that mystery and film noir--at least as it developed after the war--are primarily (but not completely) incompatible.