One Watson, One Holmes - S3-E19
Character mistake: Sherlock says "Cherchez la femme" but pronounces "femme" as "fem" rather than "fam." In earlier episodes, he has been seen speaking fluent French, and so would be unlikely to make so basic an error. (00:16:30)
Answer: I'm the same person who asked this question. I discovered it was Molly Price whom I recognized from Third Watch.
Cathrine R
It should be noted Donna was Jim Fowkes‘ secretary. Donna killed Peter.
Bishop73