Columbo already suspected that the husband was buried under the fountain as he states himself. Therefore it follows that if he can plant the seed in Nora's mind that the ring belonged to her late husband she would have to rush home to see if the garden had been dug up. When it hadn't she probably thought she was still in the clear and no one else knew her secret.

Ah ha! We have a winner.

I always thought that Nora simply had the ring among her husband's personal effects. To my mind, her panic was caused by Parks having possession of it. Imagine the questions that must have been going through her mind: Did Jean tell him where it was? If Jean led him to the ring, does that mean Jean told him the truth? And even if she didn't, will he piece it together? After all, Nora's husband was supposed to have been lost at sea; he would have been wearing his ring. Parks would start wondering how Nora could have the ring if the body was never found. The ring's existence invites Parks' suspicions.

But the above doesn't explain what Nora hoped to accomplish by rushing to her backyard fountain.

Now it makes sense. Nora would have buried her dead husband with the ring still on his finger. And now Columbo presents her with that very ring (or so she believes). She has to rush home to see if the authorities have exhumed the body or if it's all a bluff.

I see what you are saying… and by the way, this episode ending always had me puzzled too..
But anyway. Margo rushing home thinking that they had discovered her husband‘s body under the fountain Doesn’t make total sense.
If the ring was on hubs finger when she buried him and if Parks had evidence .. as in the ring, Then that would mean he would’ve been in possession of it at least the day before. She would have known that the body had been found because she would’ve been under arrest!!

It makes no sense that she went to rush home to see if it’s been been exhumed because she should’ve known she lived at the house!
The only way Parks could’ve gotten it is if he dug the body up himself because the police wouldn’t have handed it over to him.

It makes more sense that Margo was concerned that her assistant gave the ring to Parks.
That the ring was not on her husband‘s hand when it was buried.

So… it would make more sense if Margo ran to where she had kept her husband’s ring to see if the ring was still there.

So I think it is as others had suggested.. It was a knee jerk reaction just to go look at where he was buried to see if Parks had told the authorities and if they had started to dig under there.

Very nice thread.

I imagine that the writers just did this for dramatic effect, as they say. Yes, what is she planning to do? In reality her running to a back door does not prove anything. She could easily have come up with an excuse for being there. But this of course is fiction - and good fiction at that.

In reality Columbo could just as easily have confronted her about the body under the fountain, but that might have been boring.

He would need a court order to have the body removed but having Nora run to the backyard would not help him get one.

If Nora had found the fountain dug up, it maybe would have given her an opportunity to run away. Maybe that is why she immediately ran there. If the worst was true, she could pack a few things and flee before Jerry Parks recovered and told everything to the police.

Yes, Nora would flee -- to the hospital to finish off Jerry Parks before he recovers and tells everything.

But she would have to check the fountain first to see if Jerry Parks had been there digging.