Michael, you're absolutely right. The first time you watch this episode, you think she's just a regular murderer pretending to not be a murderer. But watching it again, after having the knowledge of her illness, it becomes evident that Grace has lost the memory of murdering her husband almost immediately. That scene in which she's sitting in her room and listening to Raymond the butler knocking on Henry's bedroom door is proof that she's already forgotten the murder. Janet Leigh plays the scene perfectly.

Consider, if you will, if this were a "normal" murderer such as one of Jack Cassidy's characters. Had it been a Cassidy murderer listening to Raymond knocking at Henry's door, a snide snaring smile would have crept across his face and his eyes would have twinkled with murderous glee as he admired himself in his mirror. Then he would have joined Raymond out in the hall. While Raymond continued knocking on Henry's door, the Cassidy murderer would have been checking his finger nails and would have yawned as he cried out, "Henry, oh Henry? Are you alright in there?" Then Raymond would have asked, "Shall we break down the door?" To which the Cassidy murderer would have shrugged his shoulders in boredom and responded, "Sure, why not?"

Janet Leigh's portrayl of Grace during the same scene shows for certain that the character has forgotten the murder already. She is truly frightened and worried for her husband. It's really a remarkable performance.

Great detailed analysis!!

Eric you are exactly right. When she is sitting at her vanity table looking in the mirror....wow!! what a great shot! She would not have had that expression on her face if she remembered that she had killed her husband...there was no one around to see her then.
Headache!! Great exploration into the Cassidy vs. Leigh characters.....I could actually envision Jackie boy doing all those things you said!!
I love the beauty in this episode, the romance, every actor in this is superb! It is such a rich episode in so many ways. It really is the most beautiful of all Columbo episodes.
And Matthew I agree that Columbo would have taken her in......there is a moment when he starts to approach her and he is talking, and Ned interrupts and cuts him off....I believe Columbo was about to tell her that the jig is up and he would have to arrest her...but thankfully that didn't happen.
Oh...........and Dog was in fine form in this episode!!!! I loved seeing that ice cream on his face.....little sweetie!!

I don't care for this episode for two main reasons:

1) The ending doesn't prove anything because Grace could say she was in the bathroom (a touch of stomach flu.) Or, her attorney could claim such a thing. Or maybe she just fell asleep and the film broke. There are probably more possibilites than Columbo's ideas.

2.) If Grace forgot the murder, there is no enjoyable Cat and Mouse game. Grace believes she's innocent and really does feel unjustifiably persecuted by Columbo.

John, your first point is well taken...that is a strong possibility. Her lawyers could have claimed that she was visiting the little girl's room when the film broke and then she came back and spliced the film. But somehow I think she may have asked Raymond to do that for her, since she had had such a long evening.
On your second point I just have to say that on one's initial viewing of this episode, the viewer is unaware of Grace's condition. We are not privvy to the fact that she has this brain malfunction which makes her forget the recent past...so we do still see a cat & mouse pursuit...that is, until the ending, and we realize that this woman remembers nothing of the murder. Yes there are signs.....not remembering Columbo's name...her perplexed look when Columbo visits her at the dance studio and is questioning her...just look at her face...she almost seems like she doesn't even realize her husband is dead, let alone that she killed him...but I think most people notice these things after repeated viewings, not on the first one.

Cassa, you're absolutely correct. There most definitely is a "cat and mouse" pursuit upon one's initial viewing of the episode. Leigh plays the part so incredibly perfect that you do "see" Grace as a plotting murderess all along during the first viewing of the episode. Then, once you realize that she has the disease and watch the episode again, you "see" Grace in a totally different aspect - even though it's still the exact same performance. Again, this is because Janet Leigh was such a fantastic actress.

She was wonderful, wasn't she? I agree Headache that she played this role with absolute perfection. If you just watch her face during the whole episode, the little nuances you see reveal so much about her character.
I love in the beginning when she is whirling around Henry's bedroom. She is absolutely giddy with delight. She floats around the room with such an air of sheer bliss.