He was still in there when I was there.

[Topstudent]

I wrote this:

Guy: I checked the footage, and the burglar didn't leave the room before several hours later.
Woman: So, what? He was still in there when I was there?
Guy: Yes.

Is the bold-face sentence naturally phrased?

 

[emsr2d2]

Guy Man: I checked the footage, and the burglar didn't leave the room before until several hours later.
Woman: So What? He was still in there when I was there?
Guy Man: Yes.

See above.

 

[Rover_KE]

I wrote this:

...

Who for and under what circumstances?

 

[Skrej]

I'm okay with the "So, what?" structure. I've been known to say that when I'm trying to double check my comprehension about something I've just been told.

However, I'd probably punctuate it with an ellipsis, since I trail off into a short pause before continuing with my summation.

Doctor: You have an irregular heartbeat that we can't correct with medication alone.
Me. So, what...I need a pacemaker or something?

In that context, it's completely different from the question of 'So, what?' (i.e. why does it matter/who cares). Intonation plays a role, too of course.