Sorry, I meant if she did NOT realize...

She figures it out as soon as she hears about the murder -- that's how she blackmails him (partnership, new office, future marriage, etc). And she says something like, "I wondered why you sent me out on that little research project", which apparently refers to some excuse he made, at the time, for asking her to do something as bizarre as driving through a red light while wearing a mask.

I suppose that, in TV terms, it's not implausible that a defense lawyer would want to research whether it is possible to fool a red-light camera. Plausible enough that his associate would do as she was told by her boss, without knowingly being part of a murder plot.

However, Creighton certainly should have known that she would see the real reason for her mission, as soon as the murder came to light. I figure he assumed that she'd figure it out, and that since he took her to be as unethical and unprincipled as himself, he figured it would just be a matter of money to keep her quiet.

Ted,
Thank you so much. As Lt. Columbo would say, "That explains it!"
-Lucinda