Jessica Fletcher does penace for Mrs Lovett

I've only seen Angela Lansbury in three roles: Jessica Fletcher, the amateur sleuth on TV's Murder, She Wrote; the devious mother in the film The Manchurian Candidate; and the possibly sociopathic Mrs. Lovett in the musical Sweeney Todd. Of course, Jessica Fletcher was the last of these roles that Ms Lansbury created. Was it in penance for the crimes of the other two?