Looking on the internet deeply has found these results:

No one seems to know where he is. is the most popular phrase on the web.

No one seems to know where he is at. 16 results on the web	No one seems to know where he is. 1141,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
On Tory Island, which is a strange place anyway, they were known as muldoons, and no one seems to know why. (Laughter) No one seems to know why. What that message was, no one seems to know. They say now she may have been struck by lightning, But no one seems to know for sure. There's a million theories, but no one seems to know anything. How you got out of that no one seems to know. No one seems to know, madame. No. Apparently, he's taken a leave of absence from Bass Australia, and no one seems to know where he is.	What that message was, no one seems to know. (Laughter) No one seems to know why. No. Apparently, he's taken a leave of absence from Bass Australia, and no one seems to know where he is. No one seems to know, madame. How you got out of that no one seems to know. On Tory Island, which is a strange place anyway, they were known as muldoons, and no one seems to know why. There's a million theories, but no one seems to know anything. But no one seems to know where he is.

No one seems to know where he is at.

16 results on the web

No one seems to know where he is.

1141,000 results on the web

More popular!

On Tory Island, which is a strange place anyway, they were known as muldoons, and no one seems to know why.
(Laughter) No one seems to know why.
What that message was, no one seems to know.
They say now she may have been struck by lightning, But no one seems to know for sure.
There's a million theories, but no one seems to know anything.
How you got out of that no one seems to know.
No one seems to know, madame.
No. Apparently, he's taken a leave of absence from Bass Australia, and no one seems to know where he is.

What that message was, no one seems to know.
(Laughter) No one seems to know why.
No. Apparently, he's taken a leave of absence from Bass Australia, and no one seems to know where he is.
No one seems to know, madame.
How you got out of that no one seems to know.
On Tory Island, which is a strange place anyway, they were known as muldoons, and no one seems to know why.
There's a million theories, but no one seems to know anything.
But no one seems to know where he is.