Appreciate it, Cooper. I am Chris Cuomo and welcome to Prime Time.

The coroner's verdict is in in the Gabby Petito case.

We now know Gabby was strangled and we can tell you what detail will matter most to investigators.

We also learned something else from the coroner. Here it is.

As far as the time of death, we are investigating three to four weeks from the time that the body was found.

This is an approximation. The coroner went on to say give or take a week.

The finding, however, is significant in terms of timing.

We are going to take you into the timeline and show you why.

Here is what we know. Gabby was found September 19, Wyoming's Bridger Teton National Forest, thanks to other campers.

That is how the cops found out where she was.

Dr. Blue, the coroner, says they estimate she was killed three to four weeks before she was discovered.

Now, they are always going to give a range. It is hard to know precisely.

Where does that put the death?

Approximately between August 22, which it can't be, I will explain why in a second, and the 29th.

We know we can narrow that window.

The last reported sighting of Gabby Petito by witnesses was on August 27, Mary Piglet's restaurant, Jackson, Wyoming.

If the coroner's time frame is right and the date of the last sighting is right, which we know it is,

Gabby may have been killed sometime between August 27 and August 29.

We know her fiancé, Brian Laundry, was still in the area during August 27 to August 29.

How?

Because two drivers who picked him up hitchhiking say they both gave him rides without Gabby, without Gabby.

On August 29 in the Grand Teton National Park, you'll remember he was described as seeming a little off.

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