I heard this spoken by a police officer on the “COPS” television show.

Problem:
The “at” in this statement is unnecessary.

Explanation:
I blogged about “at” last month in my “Where are you at?” post. As I wrote then, “where” implies “at” because “where” is conceptually equivalent to “at” plus a location. Therefore, “at” is unnecessary.

Beyond failing to think a second time about what the word “where” means, I believe that there is another reason why someone would say “she’s at” instead of “she is”, especially at the end of a sentence. Try saying “she’s at” and “she is”; I believe that you’ll agree with me that “she’s at” is simpler to say than is “she is”.

The phrase “she’s at” rolls off the tongue quickly as SHE-ZAT. The phrase “she is” struggles off the tongue as SHE-IZZ. Also, one must hold the IZZ part longer than one must hold the ZAT part to be understood by the listener.

In other words, the tendency of some to prefer “she’s at” over “she is” is consistent with my “Devolution toward Simpler” hypothesis.

Solution:
“I’m not sure where she is.”